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550 MHR • Science Skills Guide Science Skills Guide Science Skill Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 WHMIS Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 Science Skill Scientific Inquiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553 Making Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553 Stating an Hypothesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554 Making a Prediction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554 Identifying Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554 Designing a Fair Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555 Forming a Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556 A Process for Scientific Inquiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556 Science Skill Technological Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557 Identifying the Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557 Identifying Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557 Planning and Constructing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558 Evaluating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558 A Process for Technological Problem Solving . . . . . . . . . . . . . . . . . . . 558 Science Skill Societal Decision Making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559 Identifying the Issue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559 Gathering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559 Identifying Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560 Making a Decision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560 Evaluating the Decision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560 A Process for Societal Decision Making . . . . . . . . . . . . . . . . . . . . . . . 561 Science Skill Organizing and Communicating Scientific Results with Graphs . . . . . . . 562 Drawing a Line Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562 Constructing a Bar Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563 Constructing a Circle Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564 Independent and Dependent Variables . . . . . . . . . . . . . . . . . . . . . . . 566 Graphing on a Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567 Science Skill Scientific Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568 Making a Scientific Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568 Drawing to Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569 6 5 4 3 2 1

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  • 550 MHR • Science Skills Guide

    Science Skills GuideScience Skill Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552

    Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552WHMIS Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552

    Science Skill Scientific Inquiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553Making Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553Stating an Hypothesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554Making a Prediction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554Identifying Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554Designing a Fair Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555Forming a Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556A Process for Scientific Inquiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556

    Science Skill Technological Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557Identifying the Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557Identifying Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557Planning and Constructing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558Evaluating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558A Process for Technological Problem Solving . . . . . . . . . . . . . . . . . . . 558

    Science Skill Societal Decision Making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559Identifying the Issue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559Gathering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559Identifying Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560Making a Decision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560Evaluating the Decision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560A Process for Societal Decision Making . . . . . . . . . . . . . . . . . . . . . . . 561

    Science Skill Organizing and Communicating Scientific Results with Graphs . . . . . . . 562Drawing a Line Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562Constructing a Bar Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563Constructing a Circle Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564Independent and Dependent Variables . . . . . . . . . . . . . . . . . . . . . . . 566Graphing on a Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567

    Science Skill Scientific Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568Making a Scientific Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568Drawing to Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569

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    BCS10_BM_F_3 6/9/08 12:36 PM Page 550

  • Science Skills Guide • MHR 551

    Science Skill Estimating and Measuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570Estimating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570Measuring Length and Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570Measuring Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571Measuring Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573Measuring Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 574Measuring Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575

    Science Skill Using Models in Science . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 576

    Science Skill Using a Microscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 578

    Science Skill Chemistry Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579Periodic Table of the Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579Names, Formulas, and Charges of Some Polyatomic Ions . . . . . . . . . 580Electron Arrangements of the First 20 Elements . . . . . . . . . . . . . . . . 580Common Isotope Pairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580Boiling to Dryness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581Acid-Base Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581

    Science Skill Using Your Textbook as a Study Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . 582Using Your Textbook to Read for Information . . . . . . . . . . . . . . . . . . . 582Using Your Textbook Visuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 582Using the Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 582Using the Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583Using Graphic Organizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583

    Science Skill Units of Measurement and Scientific Notation . . . . . . . . . . . . . . . . . . . . 586The Metric System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586SI Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 587Exponents of Scientific Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 588

    Science Skill Working with Significant Digits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589Measurement and Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589Significant Digits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589Determining the Number of Significant Digits . . . . . . . . . . . . . . . . . . 589Using Significant Digits in Mathematical Operations . . . . . . . . . . . . . 590

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    BCS10_BM_F_3 6/9/08 12:36 PM Page 551

  • 552 MHR • Science Skill 1

    Safety SymbolsThe following safety symbols are used in BCScience 10 to alert you to possible dangers. Besure you understand each symbol used in anactivity or investigation before you begin.

    Disposal AlertThis symbol appears when care must be takento dispose of materials properly.

    Thermal SafetyThis symbol appears as a reminder to use caution when handling hot objects.

    Sharp Object SafetyThis symbol appears when a danger of cuts or punctures caused by the use of sharpobjects exists.

    Electrical SafetyThis symbol appears when care should betaken when using electrical equipment.

    Skin Protection SafetyThis symbol appears when use of causticchemicals might irritate the skin or when contact with micro-organisms might transmit infection.

    Clothing Protection SafetyA lab apron should be worn when this symbol appears.

    Fire SafetyThis symbol appears when care should be taken around open flames.

    Eye SafetyThis symbol appears when a danger to theeyes exists. Safety goggles should be wornwhen this symbol appears.

    Safety

    WHMIS SymbolsLook carefully at the WHMIS (WorkplaceHazardous Materials Information System)safety symbols shown here. The WHMISsymbols are used throughout Canada toidentify dangerous materials. Make certain youunderstand what these symbols mean. Whenyou see these symbols on containers, use safetyprecautions.

    Compressed Gas

    Flammable and Combustible Material

    Oxidizing Material Corrosive Material

    Poisonous and Infectious Material Causing Immediate

    and Serious Toxic Effects

    Poisonous and Infectious Material Causing Other

    Toxic Effects

    Biohazardous Infectious Material

    Dangerously Reactive Material

    Instant Practice—Safety Symbols

    Find four of the BC Science 10 safetysymbols in activities or investigations in thistextbook. For each symbol, identify thepossible dangers in the activity that thesymbol refers to.

    Instant Practice—WHMIS Symbols

    1. Find any two WHMIS symbols oncontainers in your school, or ask aparent or guardian to look for WHMISsymbols in a workplace.

    2. Record the name of the substance ineach container.

    3. What dangers are associated with thissubstance?

    Science Skill 1

    BCS10_BM_F_3 6/9/08 12:36 PM Page 552

  • Science Skill 2 • MHR 553

    Scientific InquiryThe rain has stopped, and the Sun is out. Younotice that a puddle has disappeared from thesidewalk. What happened to that puddle ofwater? You could probably quickly answer thatquestion, but how would you prove youranswer? You would need to make observationsand record data.

    Making ObservationsFirst, you might observe what happens tosome other puddles. You would watch themclosely until they disappeared and record whatyou observed.

    One observation you might make is “Thepuddle is almost all gone.” That would be aqualitative observation, an observation inwhich numbers are not used. A little later, you

    Science Skill 2

    Beginning your observations of water puddles Concluding your observations of water puddles

    Instant Practice—Making Qualitativeand Quantitative Observations

    Copy the observations below in yournotebook. Beside each write “Qual” if youthink it is a qualitative observation and “Quan”if you think it is a quantitative observation.1. (a) The cup of tea was very hot.

    (b) The refrigerator cooled the orangejuice by 18ºC.

    2. (a) The chemical indicator turned theliquid pink.

    (b) The electric guitar was louder thanthe acoustic guitar.

    3. (a) The experiment required 50 mL ofacid.

    (b) Water boils at 100ºC.4. (a) The ball hit the ground at a high

    velocity.(b) The speed limit in a school zone is

    30 km/h.5. (a) The solution was slightly acidic.

    (b) The solution had a pH of 5.2 whenmeasured.

    6. (a) It took 6.0 min to travel to the store.(b) The car is faster than the truck.

    might also say, “It took five hours for thepuddle to disappear completely.” You havemade a quantitative observation, anobservation that uses numbers.

    You probably already know that evaporationis the reason that the puddles are disappearing,but there are still lots of questions you can askabout evaporation. Although the two puddleswere the same size, one evaporated much more quickly than the other one did. Yourquantitative observations tell you that oneevaporated in 4 h, whereas the other one took 5 h. Your qualitative observations tell you thatthe one that evaporated more quickly was in theSun. The one that evaporated more slowly wasin the shade. You now have a question to ask:Does water always evaporate more quickly inthe Sun than in the shade?

    BCS10_BM_F_3 6/9/08 12:36 PM Page 553

  • 554 MHR • Science Skill 2

    Stating an HypothesisNow you are ready to make an hypothesis, astatement about an idea that you can test, basedon your observations. Your test will involvecomparing two things to find the relationshipbetween them. You know that the Sun is asource of thermal energy, so you might use thatknowledge to make this hypothesis: Evaporationfrom natural pools of water is faster for pools insunlight than for pools in shade.

    Making a PredictionAs you prepare to make your observations, youcan make a prediction, a forecast about whatyou expect to observe. In this case, you mightpredict that pools A, B, and C will dry upmore quickly than pools X, Y, and Z.

    Identifying Variables“But wait a minute,” you think, as you lookagain at your recorded observations. “Therewas a strong breeze blowing today. What effectmight that have had?” The breeze is one factorthat could affect evaporation. The Sun isanother factor that could affect evaporation.Scientists think about every possible factor thatcould affect tests they conduct. These factorsare called variables. It is important to test onlyone variable at a time.

    You need to control your variables. Thismeans that you change only one variable at atime. The variable that you change is called theindependent variable. In this case, theindependent variable is the condition underwhich you observe the puddle. One variablewould be adding thermal energy; anotherwould be moving air across it. Theindependent variable may also be called themanipulated variable.

    According to your hypothesis, addingthermal energy will change the time it takes forthe puddle to evaporate. The time in this case iscalled the dependent variable. The dependentvariable may also be called the respondingvariable.

    Instant Practice—Stating anHypothesis

    Write an hypothesis for each of thefollowing situations. You may wish to usean “If…then…” format. For example: Ifstudying affects my quiz scores, thenincreasing the amount of time I spendstudying will increase my quiz scores.1. The relationship between driver

    training and the number of caraccidents.

    2. Does the strength of an acid influencethe acid’s electrical conductivity?

    3. The relationship between atmosphericpressure and weather conditions.

    4. The relationship between types ofatmospheric gases and global warming.

    BCS10_BM_F_3 6/9/08 12:36 PM Page 554

  • Science Skill 2 • MHR 555

    (a) Find the best filter for muddy water.

    (b) Find the best plant food for plant growth.

    control(no independent

    variable)

    dependent variable

    (clarity of water)

    independentvariable(filter)

    control(no independent

    variable)

    dependent variable(growth)

    independentvariable

    (plant food) plantfood B

    plantfood A

    two layers of cheesecloth

    four layers of cheesecloth

    Instant Practice—IdentifyingVariables

    For each of the following questions, stateyour control, your independent variable,and your dependent variable.1. Does the amount of salt in salt water

    change the freezing point of thesolution?

    2. Does the temperature of the soil affectseed germination?

    3. Do objects of the same mass, butdifferent shape, fall at the same rate?

    Designing a Fair TestIf you consider more than one variable in atest, you are not conducting a fair test (onethat is valid and unbiased), and your resultswill not be useful. You will not know whetherthe breeze or the Sun made the waterevaporate.

    As you have been reading, a question mayhave occurred to you: How is it possible to doa fair test on puddles? How can you be surethat they are the same size? In situations suchas this one, scientists often use models. Amodel can be a mental picture, a diagram, aworking model, or even a mathematicalexpression. To make sure your test is fair, youcan prepare model “puddles” that you knoware all exactly the same. Science Skill 8 givesyou more information on using models.

    Often, experiments have a control. This isa test that you carry out with no variables, sothat you can observe whether yourindependent variable does indeed cause achange. Look at the illustrations below to seesome examples of variables.

    BCS10_BM_F_3 6/9/08 12:36 PM Page 555

  • 556 MHR • Science Skill 2

    A Process for Scientific InquiryOne model of the scientific inquiry process isshown in the concept map below.

    Repeat several times.

    Revise predictionor hypothesis.

    prediction or hypothesissupported

    prediction or hypothesisnot supported

    Observations and curiosity stimulate questions.

    Identify the problem.

    Gather information.

    Form an hypothesis or make a prediction.

    Perform an experiment/ investigation.

    Analyze data.

    Draw conclusions.

    Communicate results.

    The Scientific Inquiry Process

    Forming a ConclusionMany investigations are much more complexthan the one described here, and there aremany more possibilities for error. That is whyit is so important to keep careful qualitativeand quantitative observations.

    After you have completed all yourobservations, you are ready to analyze yourdata and draw a conclusion. A conclusion is astatement that indicates whether your resultssupport or do not support your hypothesis. Ifyou had hypothesized that the addition ofthermal energy would have no effect on theevaporation of water, your results would notsupport your hypothesis. An hypothesis givesyou a place to start and helps you design yourexperiment. If your results do not supportyour hypothesis, you use what you havelearned in the experiment to come up with anew hypothesis to test.

    Scientists often set up experiments withoutknowing what will happen. Sometimes theydeliberately set out to prove that somethingwill not happen.

    Eventually, when an hypothesis has been thoroughly tested and nearly all scientists agree that the results support thehypothesis, it becomes a theory.

    BCS10_BM_F_3 6/9/08 12:36 PM Page 556

  • Science Skill 3 • MHR 557

    Science Skill 3

    “Technology”—what does that word make youthink of? Do you think of complicatedelectronic equipment? Do you think of thelatest-model cars? Do you think of spaceexploration? Well, all of those have to do withtechnology, but think about this: Have youever used a pencil to flip something out of atight spot where your fingers could not reach?Have you ever used a stone to hammer basesor goal posts into the ground?

    These, too, are examples of technology.Technology is the use of scientific knowledge,as well as everyday experience, to solvepractical problems. You may not know whyyour pencil works as a lever or the physicsbehind levers, but your everyday experiencestell you how to use a lever successfully.

    Identifying the ProblemWhen you used that pencil to move the smallitem you could not reach, you did so becauseyou needed to move that item. In other words,you had identified a problem that needed tobe solved. Clearly identifying a problem is agood first step in finding a solution. In thecase of the lever, the solution was right beforeyour eyes, but finding a solution is not alwaysquite so simple.

    Suppose school is soon to close for a 16-day winter holiday. Your science class has ahamster whose life stages the class observes.Student volunteers will take the hamster homeand care for it over the holiday. However,there is a three-day period when no one willbe available to feed the hamster. Leaving extrafood in the cage is not an option because thehamster will eat it all at once. What kinds ofdevices could you invent to solve this problem?

    First, you need to identify the exact natureof the problem you have to solve. You couldstate it as follows.

    The hamster must receive food and wateron a regular basis so that it remains healthyover a certain period and does not overeat.

    Identifying CriteriaNow, how will you be able to assess how wellyour device works? You cannot invent a devicesuccessfully unless you know what criteria(standards) it must meet.

    In this case, you could use the following asyour criteria.1. Device must feed and water the hamster.2. Hamster must be thriving at the end of the

    three-day period.3. Hamster must not appear to be

    “overstuffed.”How could you come up with such a

    device? On your own, you might not. If youwork with a team, however, each of you willhave useful ideas to contribute.

    Technological Problem Solving

    BCS10_BM_F_3 6/9/08 12:36 PM Page 557

  • You might find, too, that your invention failsin a particular way. Perhaps it always leaks at acertain point where two parts are joined.Perhaps the food and water are not keptseparate. Perhaps you notice a more efficientway to design your device as you watch itoperate. Make any adjustments and test themso that your device works in the best and mostefficient way possible.

    EvaluatingWhen you are satisfied with your device, youcan demonstrate it and observe devicesconstructed by other groups. Evaluate eachdesign in terms of how well it meets the designcriteria. Think about the ideas other groupsused and why they work better than (or not aswell as) yours. What would you do differentlyif you were to redesign your device?

    A Process for Technological Problem SolvingThe problem-solving model you have just usedis shown here.

    Identify the problem.

    Decide on design criteria. .

    Solving a Technological Problem

    The design criteria were not

    satisfactory.

    Patent the product or technique for possible

    mass production.

    Use the productor technique.

    Plan and construct.• Make a sketch.

    • Draw a complete plan.• Build a model.

    Evaluate the plan.

    The product or techniqueis an excellent solution

    to the problem.

    Revisethe designcriteria.

    The plan had obviousflaws.

    Revise the plan.

    558 MHR • Science Skill 3

    Planning and ConstructingYou will probably come up with good ideas.Like all other scientists, though, you will wantto make use of information and devices thatothers have developed. Do some research andshare your findings with your group. Can youmodify someone else’s idea? With your group,brainstorm some possible designs. How wouldthe designs work? What materials would theyrequire? How difficult would they be to build?How many parts are there that could stopworking during the three-day period? Make aclear, labelled drawing of each design, with anexplanation of how it would work.

    Examine all of your suggested designscarefully. Which do you think would work best?Why? Be prepared to share your choice andyour reasons with your group. Listen carefullyto what others have to say. Do you still feelyours is the best choice, or do you want tochange your mind? When the group votes onthe design that will be built, be prepared to co-operate fully, even if the group’s choice isnot your choice.

    Get your teacher’s approval of the drawingof the design your group wants to build. Thengather your materials and build a prototype (amodel) of your design. Experiment with yourdesign to answer some questions you mighthave about it. For example, should the food and water be provided at the same time? Untilyou try it out, you may be unsure if it ispossible (or even a good idea) for yourinvention to deliver both at the same time.Keep careful, objective records of each of yourtests and of any changes you make to yourdesign.

    BCS10_BM_F_3 6/9/08 12:36 PM Page 558

  • Science Skill 4 • MHR 559

    Suppose you are part of a hockey team thatpractises at an arena in a town a few kilometresaway. Every winter, there are days when youcannot get to the arena because the roads aretoo icy. The town council is in the middle ofbudget discussions, and one of the items underdiscussion is the salting of roads. The councilis prepared to expand the salting program sothat roads in your area will be salted in winter.You and your teammates are delighted. Thiswill make your trip to the arena easier—andalways possible.

    Identifying the IssueSoon after hearing the news about the road-salting, you go to your friend’s house. Youfind your friend sitting in front of thecomputer, composing a letter to the towncouncil. In it, your friend is asking that thesalting program not be expanded to your area.You are surprised, but as you begin discussingthe letter, you start to see your friend’s pointof view.

    “What do you mean, damage theenvironment?” you ask. “Isn’t it important tomake our roads safer?”

    Gathering Information“It is,” answers your friend, “but is there someway we can make the roads safer withoutdoing so much harm to the plants at roadsidesand to the drinking water in springs and wells?I was going to research to find informationabout these questions I have written down.”

    “Whew,” you say. “There is an awful lot tothink about here. Let us see what we can findout from the Internet.”

    After researching you say, “Well, we founda lot of information, but I am still notcompletely convinced that salting the roadscould cause a problem with our water. Whatsorts of things do we need to find out in orderto answer that question?”

    “We could do an investigation,” yourfriend suggests. “Then I could use the resultsin my letter to the town council.”

    Societal Decision Making

    Science Skill 4

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  • 560 MHR • Science Skill 4

    Identifying Alternatives“I guess road salt does get into the watersystem,” you admit after completing yourinvestigation. “But we added quite a lot of salt.I wonder if any salt stays in the soil—maybewe could add less salt so that much less wouldget into the water, and our roads would still besafe for driving.”

    “Let us do some more research in thelibrary and on the Internet, and see if we canfind out how salt leaches through soil. Maybewe can also see what alternatives there are. Wecould look for something about using less salton the roads—or even no salt.”

    Making a DecisionWhen you have all of the data that yourscientific studies can provide, your decision willstill involve some very human and personalelements. People have strong feelings aboutthe social and environmental issues that affectthem. Something that seems obvious to youmight not be so obvious to another person.Even your scientific data might not change that

    person’s mind. If you are going to encourage agroup to make what you consider a gooddecision, you have to find ways to persuade thegroup to think as you do.

    After all the data are in, and after all thepersuading is done, it is time to take someaction. The seemingly small actions done byyou and your friends can have a snowballeffect. You are very keen to show your sense ofresponsibility and community spirit by gettingyour ideas across to town council when one ofyour friends makes you stop and think. “I havenoticed you putting a lot of salt out on yoursidewalk,” says your friend. “You could use abit of time and muscle power to chip away theice, but that is not the choice you make.” Yourealize your friend is right—it is not only up tothe town council or any other group to actresponsibly; it is also up to you and yourfriends. How easy is it for you to give up aneasy way of doing a task in order to make anenvironmentally responsible decision?

    Evaluating the DecisionIssues rarely have easy answers. People who areaffected have differing, valid points of view. Itis easier for you to act as an individual, but ifyou can persuade a group to act, you will havegreater influence. In the issue discussed here,you might write a letter to town council. As acompromise, you might suggest a combinationof salt and sand on the roads. Your scientificstudy can provide you with appropriatestatistics. As a group, you could attend a town

    Title:Investigation of Road Salt on Water SystemsQuestion:Does the addition of salt to soil affect thesurrounding water?Independent Variable:– saltDependent Variable:– amount of salt in waterHypothesis:– Water near soils that contain salt, will also contain salt.Prediction:– If we add salt to soil, any water that drains through

    that soil will contain salt.Procedure1.

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  • Science Skill 4 • MHR 561

    council meeting or sign a petition to makeyour views known.

    Over time, you can assess the effects ofyour actions: Are there fewer accidents on thesalted/sanded roads? Does less salt end up inthe water than when more salt alone is used?

    A Process for Societal DecisionMakingAs you reached your decision, you wentthrough various stages. Now you can thinkabout how well each stage worked and howwell you feel you completed each stage.

    Examine the flowchart below. You can seethat you used every step in this process. Aswith scientific inquiry and technologicalproblem solving, having a process to use helpsyou to focus your thinking and stay on track.

    A Process for Societal Decision Making

    Identify the issue.

    Gather relevant information.

    Identify all the alternatives.

    Consider each alternative by clarifying its consequences.

    Make a decision.

    Evaluate the decision.

    The decision is the best alternative basedon risks/benefits and,

    thus, probable consequences.

    Erro

    rs o

    f jud

    gem

    ent m

    ay h

    ave

    been

    mad

    e at

    any

    of

    thes

    e st

    eps

    in th

    e de

    cisi

    on-m

    akin

    g pr

    oces

    s.

    One or more of the stepsin the decision-making

    process were faulty. No action should be taken

    and the process should be repeated to ensure

    that the faulty steps are eliminated and replaced by

    improved thinking.

    Take action/Communicate the decision.

    Instant Practice—Making SocietalDecisions

    Before pharmaceutical products such asdrugs and cosmetics are made available tohumans, they must go through a testingprocess. Often these products are tested onanimals in a laboratory. Complete thefollowing exercise as a group of four.1. Divide your group into two pairs.2. One pair will brainstorm and record the

    advantages of animal testing and how ithas affected society in a positive way.

    3. The second pair will brainstorm andrecord the disadvantages of animaltesting, along with its negative affects onsociety.

    4. The pairs will then regroup, and bothsides can present their findings. Recordkey points on a chart for comparison.

    5. Decide which pair has the moreconvincing evidence for its view onanimal testing.

    6. As a group, brainstorm alternative waysto test new products. Choose the bestalternative, based on the informationyou have brainstormed in steps 2 and 3.

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  • 562 MHR • Science Skill 5

    Science Skill 5

    In your investigations, you will collectinformation, often in numerical form. Toanalyze and report the information, you willneed a clear, concise way to organize andcommunicate the data.

    A graph is a visual way to present data. A graph can help you to see patterns andrelationships among the data. The type ofgraph you choose depends on the type of data you have and how you want to present it.You can use line graphs, bar graphs, and circlegraphs (pie charts).

    Drawing a Line GraphA line graph is used to show the relationshipbetween two variables. The following examplewill demonstrate how to draw a line graphfrom a data table.

    Example

    Suppose you have conducted a survey to findout how many students in your school arerecycling drink containers. Out of 65 studentsthat you surveyed, 28 are recycling. To findout if more recycling bins would encouragestudents to recycle cans and bottles, you placetemporary recycling bins at three otherlocations in the school. Assume that, in afollow-up survey, you obtained the datashown in Table 1. Compare the steps in theprocedure with the graph on the next page tolearn how to make a line graph to display yourfindings.

    Procedure

    1. With a ruler, draw an x-axis and a y-axis ona piece of graph paper. (The horizontal lineis the x-axis, and the vertical line is the y-axis.)

    2. To label the axes, write “Number ofrecycling bins” along the x-axis and“Number of students using recycling bins”along the y-axis.

    3. Now you have to decide what scale to use.You are working with two numbers(number of students and number of bins).You need to show how many students usethe existing bin and how many wouldrecycle if there were a second, a third, anda fourth bin. The scale on the x-axis will gofrom 0 to 6. There are 65 students, so youmight want to use intervals of 5 for the y-axis. That means that every space on youry-axis represents 5 students. Use a tickmark at major intervals on your scale, asshown in the graph on the next page.

    4. You want to make sure you will be able to read your graph when it is complete, so make sure your intervals on the x-axis are large enough.

    5. To plot your graph, gently move a pencil up the y-axis until you reach a point just below 30 (you are representing 28 students). Now move along the line onthe graph paper until you reach the verticalline that represents the first recycling bin. Place a dot at this point (1 bin, 28students). Draw a small circle around thedot. This circle represents the inaccuracy of any measurement. Repeat this processuntil you have plotted all of the data forthe four bins.

    Organizing and Communicating Scientific Results with Graphs

    Number of Students Using Recycling BinsNumber of Bins

    1

    2

    3

    4

    Table 1 Students Using Recycling Bins

    28

    36

    48

    62

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  • Science Skill 5 • MHR 563

    6. If it is possible, draw a line that connectsall of the points on your graph. Thismight not be possible. Scientificinvestigations often involve quantities thatdo not change smoothly. On a graph, thismeans that you should draw a smoothcurve (or straight line) that most closelyfits the general shape outlined by thepoints. This is called a line of best fit. Abest-fit line often passes through many ofthe points, but sometimes it goes betweenpoints. Think of the dots on your graph asclues about where the perfect smoothcurve (or straight line) should go. A lineof best fit shows the trend of the data. Itcan be extended beyond the first and lastpoints to indicate what might happen.

    7. Give your graph a title. Based on thesedata, what is the relationship between thenumber of students using recycling binsand the number of recycling bins?

    8. How many recycling bins would berequired to have 80 students use the bins?If six bins were provided, how manystudents would be using them?

    Constructing a Bar GraphBar graphs help you to compare a numericalquantity with some other category at a glance.The second category may or may not be anumerical quantity. It could be places, items,organisms, or groups, for example.

    Example

    To learn how to make a bar graph to displaythe data in Table 3 on the next page, examinethe graph in the column next to the table asyou read the steps that follow. The data showthe number of days of fog recorded during oneyear at one weather station in each of theprovinces and territories.

    01

    Number of Recycling Bins

    Num

    ber

    of S

    tude

    nts

    Usi

    ng R

    ecyc

    ling

    Bins

    2 3 4 5 6

    10

    20

    30

    40

    50

    60

    70

    80

    90

    Instant Practice—Line Graphs

    The Moon has no atmosphere, so objectsdropped near the Moon’s surface have aconstant acceleration. The data belowrepresent the motion of such an object. Usethis data to draw a best-fit line graph of velocity versus time.

    Velocity (m/s [down])

    Time(s)

    0

    0.5

    1.0

    1.5

    2.0

    2.5

    3.0

    3.5

    4.0

    0

    0.8

    1.5

    2.4

    3.2

    4.1

    4.9

    5.5

    6.4

    Table 2 Velocity vs. Time

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  • 564 MHR • Science Skill 5

    Procedure

    1. Draw your x-axis and y-axis on a sheet ofgraph paper. Label the x-axis with the namesof the provinces and territories and the y-axis with the average number of days of fog.

    2. Look at the data carefully in order to selectan appropriate scale. Write the scale of youry-axis.

    3. Decide on a width for the bars that will belarge enough to make the graph easy toread. Leave the same amount of spacebetween each bar.

    4. Using Newfoundland and 206 as the firstpair of data, move along the x-axis thewidth of your first bar, then go up the y-axis to 206. Use a pencil and ruler todraw in the first bar lightly. Repeat thisprocess for the other pairs of data.

    5. When you have drawn all of the bars, youmight want to colour them so that eachone stands out. If you have no colours, youcould use cross-hatching, dots, or diagonallines to distinguish one bar from another.

    6. If you are comparing two or moremanipulated variables that you have plottedon the x-axis, you will need to make alegend or key to explain the meaning ofthe colours. Write a title for your graph.

    Constructing a Circle GraphA circle graph (sometimes called a pie chart)uses a circle divided into sections (pieces ofpie) to show the data. Each section representsa percentage of the whole. All sectionstogether represent all (100 percent) of thedata.

    Number of Days of FogProvince

    Newfoundland

    Prince Edward Island

    New Brunswick

    Nova Scotia

    Québec

    Ontario

    Manitoba

    Saskatchewan

    Alberta

    British Columbia

    Yukon Territory

    Northwest Territories

    Table 3 Average Number of Days of Fog per Year in Canadian Provinces and Territories (prior to April 1, 1999)

    206

    47

    106

    127

    85

    76

    48

    37

    39

    226

    61

    196

    NewfoundlandPrince Edward IslandNew BrunswickNova ScotiaQuébecOntario

    ManitobaSaskatchewanAlbertaBritish ColumbiaYukon TerritoryNorthwest Territories

    50

    100

    150

    200

    250

    Average Number of Days of Fog per Year in Canadian Provinces and Territories before April 1, 1999

    Aver

    age

    Num

    ber

    of D

    ays

    of F

    og

    Instant Practice—Bar Graphs

    Construct a bar graph to display the datashowing the average yearly precipitationin several British Columbia locations.

    Average Annual Precipitation (mm)

    Location

    Ashcroft

    Fort St. James

    Kamloops

    Kelowna

    Prince Rupert

    Smithers

    Vancouver

    Victoria

    206

    47

    279

    366

    2593

    325

    1219

    608

    Table 4 Comparison of Precipitation

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  • Science Skill 5 • MHR 565

    Example

    To learn how to make a circle graph from thedata in Table 5, study the corresponding circlegraph on the right as you read the followingsteps.

    Procedure

    1. Use a mathematical compass to make alarge circle on a piece of paper. Make a dotin the centre of the circle.

    2. Determine the percent of the total numberof species that each type of bird representsby using the following formula.

    Percent of total �

    For example, the percent of all species of birds that are ducks is:

    Percent that �

    are ducks

    3. To determine the degrees in the sectionthat represents each type of bird, use thefollowing formula.

    Degrees in �

    “piece of pie”

    Round your answer to the nearest whole number. For example, the section for ducks is:

    Degrees for ducks �

    4. Draw a straight line from the centre to theedge of the circle. Use your protractor tomeasure 32° from this line. Make a mark,then use your mark to draw a second line32° from the first line.

    5. Repeat steps 2 to 4 for the remaining types of birds.

    Type of BirdNumber

    of SpeciesDegrees in

    SectionPercent of Total

    Ducks

    Birds of prey

    Shorebirds

    Owls

    Perching birds

    Other

    36

    19

    71

    14

    180

    80

    9.0

    4.8

    17.7

    3.5

    45.0

    20.0

    32

    17

    64

    13

    162

    72

    Table 5 Birds Breeding in Canada

    Species of Birds Breeding in Canada

    owlsshorebirds birds of prey

    ducks

    other

    perching birds

    Instant Practice—Circle Graph

    There are more than 70 elements dissolvedin sea water. Make a circle graph using theelements in the table below.

    Percent of Sea Water Element

    calcium (Ca)

    chloride (Cl)

    magnesium (Mg)

    potassium (K)

    sodium (Na)

    Other

    1.2

    55.0

    3.7

    1.1

    31.0

    8.0

    Table 6 Elements in Sea Water

    Number of species within the typeTotal number of species � 100%

    � 100% � 9.0%36 species of ducks

    400 species

    � 360°Percent for a type of bird

    100%

    � 360° � 32.4° or 32°9.0%100%

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  • 566 MHR • Science Skill 5

    Line graphs and bar graphs are often used toshow the relationship between two variables.A variable is a quantity that can change. Thedata from an experiment usually contain anindependent variable and a dependentvariable. The independent variable is the onethat the experimenter changes. This variable isusually plotted on the x-axis (horizontal axis).The dependent variable responds to thechange in the independent variable. Thedependent variable is usually plotted on the y-axis (vertical axis), as shown below.

    The first step in drawing a graph ofexperimental data is to analyze the procedureand data to determine the dependent andindependent variables. For example, when youare learning to drive, you find that after youstep on the brakes, the distance your cartravels before it stops depends on how fastyou were travelling. Suppose we set up anexperiment in which a car is driven at differentspeeds and the distance it travels, after thebrakes are applied, is recorded. The data forthis experiment are displayed in Table 7.

    In this experiment, the procedure was tochange the speed of the car and measure thebraking distance. The variable that theexperimenter changed was the speed. Therefore,speed is the independent variable and should beplotted on the x-axis. The braking distancevaried as a result of the changes in speed andtherefore is the dependent variable. The brakingdistance is plotted on the y-axis, as shown below.

    Braking Distance (m)Speed (km/h)

    30

    40

    50

    60

    70

    80

    Table 7 Relation of Braking Distance to Speed

    6.0

    10.5

    16.5

    23.6

    32.0

    42.0

    Independent Variable

    Dep

    ende

    nt V

    aria

    ble

    Independent Variable

    Dep

    ende

    nt V

    aria

    ble

    Speed (km/h)

    Brak

    ing

    Dis

    tanc

    e (m

    )

    0 10 20 30 40 50 60 70 80

    51015202530354045505560

    Speed (km/h)

    Brak

    ing

    Dis

    tanc

    e (m

    )

    0 10 20 30 40 50 60 70 80

    51015202530354045505560

    Instant Practice—Independent andDependent Variables

    1. State the independent variable anddependent variable for each of the graphsbelow.

    2. By a busy street, an experimenter recordsthe amount of time, in seconds, requiredfor every 25 cars to pass. State theindependent and dependent variables inthis description.

    Independent and Dependent Variables

    Month

    Ave

    rage

    Tem

    pera

    ture

    (°C)

    0

    6

    12

    18

    24

    30

    Time (s)

    Velo

    city

    (m/s

    )

    0 4 128 16 2420

    10

    30

    50

    70

    90

    110[N]

    J F M A M J J A S O N D

    A B

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  • Science Skill 5 • MHR 567

    Graphing on a ComputerComputers are a useful tool for graphpreparation for the following reasons.1. Data need be entered only once. As many

    graphs as you need can then be preparedwithout any more data entry.

    2. Once the data are entered, you can use thecomputer to manipulate them. You canchange the scale, zoom in on importantparts of the graph, graph different parts ofthe data in different ways, and so on—allwithout doing any calculations!

    3. Computers prepare graphs far more quicklythan people working carefully.

    4. Computers can be hooked up to sensors(thermometers, timers, etc.), so you do notneed to read instruments and enter data byhand, with all the resulting possibilities forerror. The computer can display thereadings on a graph as data are collected(in “real” time), so you can quickly get apicture of how your experiment is going.

    5. Errors can be corrected much more easilywhen working with a computer. Justcorrect the error and print again.

    6. Computer graphs can be easily insertedinto written lab reports, magazine articles,or Internet pages. It is possible to scanhand-drawn graphs into a computer, but itis not easy to do it well, and the resultingfiles are very large.

    7. Once data have been entered into acomputer, the computer can determine aline of best fit and a mathematical equationthat describes the line. This line can helpyou to discover patterns in your data andmake predictions to test your inferences.

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  • 568 MHR • Science Skill 6

    Have you ever used a drawing to explainsomething that was too difficult to explain inwords? A clear drawing can often assist orreplace words in a scientific explanation.In science, drawings are especially importantwhen you are trying to explain difficultconcepts or describe something that contains alot of detail. It is important to make scientificdrawings clear, neat, and accurate.

    Examine the drawing shown below. It istaken from a student’s lab report on anexperiment to test the expansion of air in aballoon. The student’s written description ofresults included an explanation of how theparticle model can explain what happens to theballoon when the bottle is placed in hot waterand in cold water. As you can see, the cleardiagrams of the results can support or evenreplace many words of explanation. While yourdrawing itself is important, it is also importantto label it clearly. If you are comparing andcontrasting two objects, label each object anduse labels to indicate the points of comparisonbetween them.

    Making a Scientific DrawingFollow these steps to make a good scientificdrawing.1. Use unlined paper and a sharp pencil with

    an eraser.2. Give yourself plenty of space on the paper.

    You need to make sure that your drawing willbe large enough to show all necessary details.You also need to allow space for labels. Labelsidentify parts of the object you are drawing.Place all of your labels to the right of yourdrawing, unless there are so many labelsthat your drawing looks cluttered.

    3. Carefully study the object that you will bedrawing. Make sure you know what youneed to include.

    4. Draw only what you see, and keep yourdrawing simple. Do not try to indicate partsof the object that are not visible from theangle you observed. If you think it isimportant to show another part of the object,do a second drawing, and indicate the anglefrom which each drawing is viewed.

    5. Shading or colouring is not usually used in scientific drawings. If you want to indicatea darker area, you can use stippling (a seriesof dots). You can use double lines toindicate thick parts of the object.

    Scientific Drawing

    Science Skill 6

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  • Science Skill 6 • MHR 569

    6. If you do use colour, try to be as accurateas you can and choose colours that are asclose as possible to the colours in theobject you are observing.

    7. Label your drawing carefully andcompletely, using lower-case (small) letters.Think about what you would need toknow if you were looking at the object forthe first time. Remember to place all yourlabels to the right of the drawing, ifpossible. Use a ruler to draw a horizontalline from the label to the part you areidentifying. Make sure that none of yourlabel lines cross.

    8. Give your drawing a title. The drawing of a human skin cell shown below is from astudent’s notebook. This student usedstippling to show darker areas, horizontallabel lines for the cell parts viewed, and atitle—all elements of an excellent finaldrawing.

    The stippling on this drawing of a human skin cell showsthat some areas are darker than others.

    Drawing to ScaleWhen you draw objects seen through amicroscope, the size of your drawing isimportant. Your drawing should be inproportion to the size of the object as theobject appears when viewed through themicroscope. This type of drawing is called ascale drawing. A scale drawing allows you tocompare the sizes of different objects and toestimate the actual size of the object being

    viewed. Here are some steps to follow whenmaking scale drawings of magnified objects.1. Use a mathematical compass to draw an

    accurate circle in your notebook. The sizeof the circle does not matter. The circlerepresents the microscope’s field of view.

    2. Imagine the circle is divided into fourequal sections (see the diagram below).Use a pencil and a ruler to draw thesesections in your circle, as shown here.

    3. Using low or medium power, locate anobject under the microscope. Imagine thatthe field of view is also divided into fourequal sections.

    4. Observe how much of the field of view istaken up by the object. Note the locationof the object in the field of view.

    5. Draw the object in the circle. Position theobject in about the same part of the circleas it appears in the field of view. Draw theobject so that it takes up about the sameamount of space within the circle as it takesup in the field of view, as shown in thediagram.

    drawing made to scale (100x)

    field of view under the microscope (100x) divided into four equal sections

    =

    Instant Practice—Scale Drawings

    Place three objects on top of your desk (forexample, a textbook, an eraser, and acalculator). Design a scale drawing of thetop of your desk, using the shape of thedesktop rather than a circle as in theexample above. Include the shape andlocation of each object in your diagram.

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  • 570 MHR • Science Skill 7

    Measuring Length and AreaYou can use a metre stick or a ruler to measureshort distances. These tools are usually markedin centimetres and/or millimetres. Use a rulerto measure the length in millimetres betweenpoints A and F, C and E, F and B, and A andD. Convert your measurements to centimetresand then to metres.

    To calculate an area, you can use lengthmeasurements. For example, for a square or arectangle, you can find the area by multiplyingthe length by the width.

    Area of square is 4 cm � 4 cm = 16 cm2.

    Area of rectangle is 18 mm � 12 mm � 216 mm2.

    Make sure you always use the same units—if you mix up centimetres and millimetres,your calculations will be wrong. Remember toask yourself if your answer is reasonable (youcould make an estimate to consider this).

    EstimatingHow long will it take you to read this page?How heavy is this textbook? What is the heightof your desk? You could probably answer all ofthese questions by estimating—making aninformed judgement about a measurement. Anestimate gives you an idea of the measure butis not an exact measurement.

    Scientists often make estimates when exactmeasurements are not essential. You will find ituseful to be able to estimate as accurately aspossible, too. For example, suppose youwanted to know how many ants live in a localpark. Counting every ant would be very time-consuming—and the ants would be mostunlikely to stay in one spot for yourconvenience! What you can do is count thenumber of ants in a typical square-metre area.Multiply the number of ants by the number ofsquare metres in the total area you areinvestigating. This will give you an estimate ofthe total population of ants in that area.

    Estimating and Measuring

    Science Skill 7

    A

    C E

    B

    D

    F

    4 cm

    4 cm

    18 mm

    12 mm

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  • Science Skill 7 • MHR 571

    Measuring VolumeThe volume of an object is the amount of spacethat the object occupies. There are several waysof measuring volume, depending on the kindof object you want to measure. A cubic metreis the space occupied by a 1 m � 1 m � 1 mcube. This unit of volume is used to measurelarge quantities, such as the volume ofconcrete in a building. In this course, you aremore likely to use cubic centimetres (cm3) orcubic millimetres (mm3) to record the volumeof an object.

    You can calculate the volume of a cube bymultiplying its sides. For example, volume � 1 cm � 1 cm � 1 cm � 1 cm3.

    You can calculate the volume of a rectangularsolid if you know its length, width, and height.

    volume � length � width � height

    If all the sides are measured in millimetres(mm), the volume will be in cubic millimetres(mm3). If all the sides are measured incentimetres (cm), the volume will be in cubiccentimetres (cm3). The units for measuring thevolume of a solid are called cubic units.

    Instant Practice—Estimating

    1. An elevator has a maximum carryingcapacity of 1200 kg. If the averageperson has a mass of 60 kg, estimate thenumber of people this elevator can safelyhold.

    2. A 747 jet has a wingspan of 70 m. If theaverage person is 1.7 m tall, estimate thelength of the wings measured in humanbody lengths.

    3. You purchase a 350 g bag of almondsfrom the store. How can you make agood estimate of the number ofalmonds in the bag?(a) Decide how you can use a centigram

    balance and a small number ofalmonds to estimate the totalnumber of almonds in the bag.

    (b) Carry out your plan.(c) Compare your results with those of

    two or three classmates.

    Instant Practice—Measuring Lengthand Area

    1. The dimensions of a CFL football fieldand a tennis court are as follows:Football field – 102 m � 60 m Tennis court – 24 m � 11 m(a) Calculate the area of the CFL

    football field. (b) Calculate the area of the tennis

    court. 2. Measure the dimensions of the front

    cover of your BC Science 10 textbook.Calculate the area of the cover in m2.

    3. State how many BC Science 10 coversare needed to cover the surface of:(a) the football field(b) the tennis court

    BCS10_BM_F_3 6/9/08 12:36 PM Page 571

  • 572 MHR • Science Skill 7

    The units used to measure the volume of liquids are called capacity units. The basic unitof volume for liquids is the litre (L). In thiscourse, you also measure volume usingmillilitres (mL). Recall that 1 L � 1000 mL.You have probably seen capacity in litres andmillilitres printed on juice, milk, and soft drinkcontainers.

    Cubic units and capacity units areinterchangeable. For example:

    1 cm3 � 1 mL1 dm3 � 1 L1 m3 � 1 kL

    The volume of a liquid can be measureddirectly, as shown in Diagram B. Make sureyou measure to the bottom of the meniscus,the slight curve where the liquid touches thesides of the container. To measure accurately,make sure your eye is at the same level as thebottom of the meniscus.

    Measuring the volume of a liquid

    The volume of an irregularly shaped solidobject, however, must be measured indirectlyas shown in Diagram C. This is done bydetermining the volume of a liquid it willdisplace.

    1. Record the volume of the liquid.

    2. Carefully lower the object intothe cylinder containing theliquid. Record the volume again.

    3. The volume of the object isequal to the difference betweenthe two volumes of the liquid.The equation below thephotograph shows you how tocalculate this.

    Measuring the volume of an irregularly shaped solid

    volume of object � volume of water with object � original volume of water� 85 mL � 60 mL� 25 mL

    1 2 3

    4 cm

    4 cm

    4 cm

    6 cm

    5 cm

    3 cm

    4 cm × 4 cm × 4 cm = 64 cm3 5 cm × 6 cm × 3 cm = 90 cm3

    graduated cylinder

    line where liquid touches glass

    meniscus

    liquid

    too high

    too low

    read here

    60

    50

    40

    30

    90

    80

    70

    100

    A

    B

    C

    As you can see in Diagram A, the volume of a regularly shaped solid object can be measured directly.

    Measuring the volume of a regularly shaped solid

    BCS10_BM_F_3 6/9/08 12:36 PM Page 572

  • Science Skill 7 • MHR 573

    Measuring MassIs your backpack heavier than your friend’s backpack? You can check by holding abackpack in each hand. The mass of an objectis the amount of matter in a substance orobject. Mass is measured in milligrams, grams,kilograms, and tonnes. You need a balance,such as a triple beam balance, for measuringmass.

    Use the following steps to measure themass of a solid object.1. Set the balance to zero. Do this by sliding all

    three riders back to their zero points. Usingthe adjusting screw, make sure the pointerswings an equal amount above and belowthe zero point at the far end of the balance.

    2. Place the object on the pan. Observe what happens to the pointer.

    3. Slide the largest rider along until thepointer is just below zero. Then move itback one notch.

    4. Repeat with the middle rider and then withthe smallest rider. Adjust the last rider untilthe pointer swings equally above and belowzero again.

    5. Add the readings on the three scales to find the mass.

    How can you find the mass of a certainquantity of a substance, such as table salt, thatyou have added to a beaker? First, find themass of the beaker. Next, pour the salt into thebeaker and find the mass of the beaker and salttogether. To find the mass of the salt, simplysubtract the beaker’s mass from the combinedmass of the beaker and salt.

    The mass of the beaker is 160 g.

    Instant Practice—Measuring Volume

    1. Write the steps you would take to findthe volume of a rock, using agraduated cylinder containing water.

    2. Determine the volume of liquid ineach of these graduated cylinders.

    C

    A

    B

    BCS10_BM_F_3 6/9/08 12:36 PM Page 573

  • 574 MHR • Science Skill 7

    Measuring AnglesYou can use a protractor to measure angles.Protractors usually have an inner scale and anouter scale. The scale you use depends on howyou place the protractor on an angle (symbol��). Look at the following examples to learnhow to use a protractor.

    Example 1

    What is the measure of �XYZ?

    SolutionPlace the centre of the protractor on point Y.YX crosses 0° on the outer scale. YZ crosses 70°on the outer scale. So �XYZ is equal to 70°.

    Example 2

    Draw �ABC � 155°.

    SolutionFirst, draw a straight line, AB. Place the centreof the protractor on B and line up AB with 0°on the inner scale. Mark C at 155° on theinner scale. Join BC. The angle you havedrawn, �ABC, is equal to 155°.

    XY

    Z

    Instant Practice—Measuring Mass

    1. A friend gives you two identical juicebottles. One is empty, and the other isfull and unopened. Write the steps youwould take to find the mass of only thejuice, without opening the bottle.

    2. Determine the masses represented onthe following centigram balances.

    0 100 200g

    0 10 20 30 40 50 60 70 80 90 100g

    0 1 2 3 4 5 6 7 8 9 10g

    0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.10g

    0 100 200g

    0 10 20 30 40 50 60 70 80 90 100g

    0 1 2 3 4 5 6 7 8 9 10g

    0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.10g

    0 100 200g

    0 10 20 30 40 50 60 70 80 90 100g

    0 1 2 3 4 5 6 7 8 9 10g

    0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.10g

    A

    B

    C

    The mass of the table salt and beaker together is 230 g.Therefore, the mass of the salt is 70 g.

    BCS10_BM_F_3 6/9/08 12:37 PM Page 574

  • Measuring Temperature Temperature is a measure of the thermalenergy of the particles of a substance. In thevery simplest terms, you can think oftemperature as a measure of how hot or howcold something is. The temperature of amaterial is measured with a thermometer.

    For most scientific work, temperature is measured on the Celsius scale. On this scale,the freezing point of water is zero degrees(0°C) and the boiling point of water is 100 degrees (100°C). Between these points,the scale is divided into 100 equal divisions.Each division represents one degree Celsius.On the Celsius scale, average human bodytemperature is 37°C and a typical roomtemperature may be between 20°C and 25°C.

    The SI unit of temperature is the kelvin(K). Zero on the Kelvin scale (0 K) is thecoldest possible temperature. This temperature

    is also known as absolute zero. It is equivalentto �273°C, which is about 273 degrees belowthe freezing point of water. Notice that degreesymbols are not used with the Kelvin scale.

    Most laboratory thermometers are markedonly with the Celsius scale. Because thedivisions on the two scales are the same size,the Kelvin temperature can be found byadding 273 to the Celsius reading. This meansthat on the Kelvin scale, water freezes at 273 Kand boils at 373 K.

    Tips for using a thermometer

    When using a thermometer to measure thetemperature of a substance, here are threeimportant tips to remember.• Handle the thermometer extremely

    carefully. It is made of glass and can breakeasily.

    • Do not use the thermometer as a stirringrod.

    • Do not let the bulb of the thermometertouch the walls of the container.

    Science Skill 7 • MHR 575

    010

    0

    Instant Practice—Measuring Angles

    1. State the measure of each of the followingangles using the diagram below.(a) �DAE (d) �HAG (g) �EAH(b) �DAG (e) �GAE (h) �EAF(c) �IAF (f) �DAH (i) �FAI

    2. Use a protractor to draw angles with thefollowing measures. Label each angle.(a) DEF 30° (c) DEF 40°(b) XYZ 75° (d) PQR 15°

    100 110 120130

    140150

    160170

    180

    8070

    60

    50

    40

    3020

    100

    100110

    120

    130

    140

    150

    160

    170

    180

    80 7060

    50

    4030

    2010

    0

    90

    AD

    E

    FG

    H

    I

    BCS10_BM_F_3 6/9/08 12:37 PM Page 575

  • 576 MHR • Science Skill 8

    When you think of a model, you might thinkof a toy such as a model airplane. Is a modelairplane similar to a scientific model? Ifbuilding a model airplane helps you learnabout flight, then you could say it is a scientificmodel.

    In science, a model is anything that helpsyou better understand a scientific concept. Amodel can be a picture, a mental image, astructure, or even a mathematical formula.Sometimes, you need a model because theobjects you are studying are too small to seewith the unaided eye. You may have learnedabout the particle model of matter, forexample, which is a model that states that allmatter is made of tiny, invisible particles.Sometimes a model is useful because theobjects you are studying are extremely large—the planets in our solar system, for example. Inother cases, the object may be hidden fromview, like the interior of Earth or the inside ofa living organism. A mathematical model canshow you how to perform a calculation.

    Scientists often use models to communicatetheir ideas to other scientists or to students.They also use models to test an idea, to findout if an hypothesis is supported, and to plannew experiments in order to learn more aboutthe subject they are studying. Sometimes,scientists discover so much new informationthat they have to modify their models.Examine the models in the illustrations on thispage. How can these models help you learnabout science?

    You can learn about day and night by using a globe and aflashlight to model Earth and the Sun.

    Using Models in Science

    Science Skill 8

    The particles shown here are models representing theatoms and molecules of a gas.

    Instant Practice—Using Models

    Certain genetic traits are passed down fromyour ancestors. Dark hair is a dominant trait. 1. Draw a diagram of your heritage “family

    tree,” starting with your grandparents.2. Identify, with a dark circle, each person

    on the family tree that has dark hair.3. Using this model of your heritage,

    explain what the statement “Dark hair isdominant” means.

    4. Suggest another use for the model youjust drew.

    BCS10_BM_F_3 6/9/08 12:37 PM Page 576

  • Science Skill 9 • MHR 577

    The light microscope is an optical instrumentthat greatly increases our powers ofobservation by magnifying objects that areusually too small to be seen with the unaidedeye. The microscope you will use is called acompound light microscope because it uses aseries of lenses (rather than only one as in amagnifying glass) and it uses light to view theobject.

    A microscope is a delicate instrument, soyou must use proper procedure and care. ThisScience Skill reviews the skills that you willneed to use a microscope effectively. Beforeyou use your microscope, you need to knowthe parts of a microscope and their functions.

    Using a Microscope

    B. TubeThe tube holds the eyepieceand the objective lenses atthe proper working distancefrom each other.

    C. Revolving nosepieceThis rotating disk holds twoor more objective lenses. Turnit to change lenses. Each lensclicks into place.

    D. Objective lensesThe objective lenses magnifythe object. Each lens has adifferent power ofmagnification, such as 4�,10�, 40�. (Your microscopemay instead have 10�, 40�,and 100� objective lenses.)The objective lenses arereferred to as low, medium,and high power. Themagnifying power isengraved on the side of eachobjective lens. Be sure youcan identify each lens.

    E. ArmThe arm connects the baseand the tube. Use the arm forcarrying the microscope.

    F. Coarse focus knobThe coarse focus knob movesthe tube up and down tobring the object into focus.Use it only with the low-power objective lens.

    G. Fine focus knobUse the fine focus knob withmedium- and high-powermagnification to bring theobject into sharper focus.

    H. StageThe stage supports themicroscope slide. Stage clipshold the slide in position. Anopening in the centre of thestage allows light from thelight source to pass throughthe slide.

    I. Condenser lensThe condenser lens directslight to the object beingviewed.

    J. DiaphragmThe diaphragm controls the amount of light reaching the object being viewed.

    A. Eyepiece (or ocular lens)You look through the eyepiece. It has alens that magnifies the object, usually by10 times (10�). The magnifying power isengraved on the side of the eyepiece.

    K. Light sourceShining a light through the object beingviewed makes it easier to see the details.If your microscope has a mirror instead ofa light, adjust the mirror to direct lightthrough the lenses. CAUTION: Use anelectric light, not sunlight, as the lightsource for focussing your mirror.

    A

    B

    C

    D

    E

    F

    G

    H

    I

    K

    J

    Science Skill 9

    BCS10_BM_F_3 6/9/08 12:37 PM Page 577

  • 578 MHR • Science Skill 9

    Instant Practice—Field of View

    The field of view is the entire area you seewhen you look through a microscope. Thediameter of the field of view is the distancefrom one side of the view to the other. Thisdiameter varies with the magnification. Thediameter can be used to estimate the size ofthe object being viewed.1. Rotate the low-power objective lens into

    position.2. Place a transparent metric ruler,

    calibrated in mm, on the stage so thatthe edge of the ruler crosses the centreof the field of view, as shown below.

    3. Using the adjustment knob(s), bring theruler into clear focus.

    4. Record the diameter of the field of view.5. Repeat steps 2 to 4 for the medium-

    power objective lens.6. Make a wet-mount slide of one of the

    hairs from your head.7. Place the slide on the stage and view it

    on low power. Using the diameter ofthe field of view you recorded, estimatethe thickness of your hair.

    8. Repeat step 7 using medium power.

    TroubleshootingYou may encounter difficulties when usingyour microscope. The following list details themore common problems and how you can dealwith them.• You cannot see anything. Make sure the

    microscope is plugged in and the light isturned on. If the microscope has no light,adjust your mirror.

    • Are you having trouble finding anything onthe slide? Be patient. Make sure the objectbeing viewed is in the middle of the stageopening. While watching from the side,lower the low-power objective as far as itwill go. Then look through the ocular lensand slowly raise the objective lens using thecoarse-adjustment knob.

    • Are you having trouble focussing, or is theimage very faint? Try closing the diaphragmslightly. Some objects are almosttransparent. If there is too much light, aspecimen may be difficult to see or willappear “washed out.”

    • Do you see lines and specks floating across theslide? These are probably structures in thefluid of your eyeball that you see when youmove your eyes. Do not worry; this isnormal.

    • Do you see a double image? Check that theobjective lens is properly clicked into place.

    • Do you close one eye while you look through themicroscope with the other eye? You might trykeeping both eyes open. This will helpprevent eye fatigue. It also lets you sketchan object while you are looking at it.

    • Always place the part of the slide you areinterested in at the centre of the field ofview before changing to a higher-powerobjective lens. Otherwise, when you turn tomedium and high power, you may not seethe object you were viewing under lowpower.

    BCS10_BM_F_3 6/9/08 12:37 PM Page 578

  • Science Skill 10 • MHR 579

    Chemistry Reference

    Science Skill 10

    BCS10_BM_F_3 6/9/08 12:37 PM Page 579

  • Names, Formulas, and Charges ofSome Polyatomic Ions

    FormulaName

    acetate CH3COO�

    ammonium NH4�

    carbonate CO32�

    chlorate ClO3�

    chlorite ClO2�

    chromate CrO42�

    cyanide CN�

    dichromate Cr2O72�

    hydrogen carbonate, bicarbonate HCO3�

    hydrogen sulfate, bisulfate HSO4�

    hydrogen sulfide, bisulfide HS�

    hydrogen sulfite, bisulfite HSO3�

    hydroxide OH�

    hypochlorite ClO�

    nitrate NO3�

    nitrite NO2�

    perchlorate ClO4�

    permanganate MnO4�

    phosphate PO43�

    phosphite PO33�

    sulfate SO42�

    sulfite SO32�

    IonAtom

    Electron Arrangements of the First20 Elements

    H

    He

    Li

    Be

    B

    C

    N

    O

    F

    Ne

    Na

    Mg

    Al

    Si

    P

    S

    Cl

    Ar

    K

    Ca

    1 p

    2 p

    3 p

    4 p

    5 p

    6 p

    7 p

    8 p

    9 p

    10 p

    11 p

    12 p

    13 p

    14 p

    15 p

    16 p

    17 p

    18 p

    19 p

    20 p

    1

    2

    2, 1

    2, 2

    2, 3

    2, 4

    2, 5

    2, 6

    2, 7

    2, 8

    2, 8, 1

    2, 8, 2

    2, 8, 3

    2, 8, 4

    2, 8, 5

    2, 8, 6

    2, 8, 7

    2, 8, 8

    2, 8, 8, 1

    2, 8, 8, 2

    H�

    H�

    He

    Li�

    Be2�

    B3�

    C4�

    N3�

    O2�

    F�

    Ne

    Na�

    Mg2�

    Al3�

    Si4�

    P3�

    S2�

    Cl�

    Ar

    K�

    Ca2�

    1 p

    1 p

    3 p

    4 p

    5 p

    6 p

    7 p

    8 p

    9 p

    11 p

    12 p

    13 p

    14 p

    15 p

    16 p

    17 p

    19 p

    20 p

    0

    2

    2

    2

    2

    2, 8

    2, 8

    2, 8

    2, 8

    2, 8

    2, 8

    2, 8

    2, 8, 8

    2, 8, 8

    2, 8, 8

    2, 8, 8

    2, 8, 8

    2, 8, 8

    Does not form an ion

    Does not form an ion

    Does not form an ion

    580 MHR • Science Skill 10

    Common Isotope Pairs

    DaughterEffective Dating

    Range (years)Half-Life of

    Parent (years)

    carbon-14

    uranium-235

    potassium-40

    uranium-238

    thorium-235

    rubidium-87

    nitrogen-14

    lead-207

    argon-40

    lead-206

    lead-208

    strontium-87

    5730

    710 million

    1.3 billion

    4.5 billion

    14 billion

    47 billion

    up to 50 000

    >10 million

    10 000 to 3 billion

    >10 million

    >10 million

    >10 million

    Common Isotope Pairs

    IsotopeParent

    BCS10_BM_F_3 6/9/08 12:37 PM Page 580

  • Science Skill 10 • MHR 581

    Boiling to DrynessIf you want to get a solid sample of acompound dissolved in a liquid, you can oftenuse the “boiling to dryness” method. In thisprocedure, you heat the solution in a test tubeover a flame until all the water has boiled off.Here are some points to help ensure successand safety.• First, make sure that the solid will not react

    or decompose when heated. If it will, youcannot get a pure sample of the substanceby the boiling method. For thesecompounds, evaporation at roomtemperature might work better.

    • Use boiling chips. These are small solidlumps of a non-reactive substance such asglass. Boiling chips have a rough surface,giving them a large surface area. Bubbles ofsteam will develop on them and prevent“bumping,” the sudden formation of largebubbles. Bumping can cause the solution tospatter out of the test tube.

    • Be sure to hold the test tube in the flame ata 45° angle, as shown in the photograph.Do not hold the test tube straight up anddown, or the solution at the bottom mayboil too quickly and shoot out of the top.

    • Keep the flame near the top level of thesolution so the liquid will boil withoutspattering.

    • As the solution dries, the danger ofspattering increases. Heat slowly and, ifnecessary, remove the test tube from theflame for a few seconds. Be patient.

    Methyl orange

    BasicAcidic Neutral

    Methyl red

    Bromothymol blue

    Litmus

    Phenolphthalein

    Indigo carmine

    Red

    Red

    Yellow

    Red

    Colourless

    Blue

    Yellow

    Yellow

    Blue

    Pink

    Yellow

    Blue

    0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

    pH

    Acid-Base Indicators

    BCS10_BM_F_3 6/9/08 12:37 PM Page 581

  • 582 MHR • Science Skill 11

    How can you use your textbook effectively tounderstand science concepts better? ThisScience Skill will give you strategies to help youbetter understand what you read. It will alsoexplain how to use textbook visuals anddescribe different types of graphic organizersthat can help you organize your information.

    Using Your Textbook to Read forInformationReading a textbook is different from reading anovel or magazine. A textbook contains manydifferent terms and concepts that you mustunderstand and apply throughout each section.Here are several strategies to help you recordthe information.1. Before reading a section, scan the pages.

    While you are scanning, look at thepictures and try to predict what you thinkthe section will be about. Try to figure outthe definitions for bolded words with thehelp of the Glossary or from the sentencethe bolded word is in.

    2. A light brown shaded box at the beginningof each section summarizes the key ideascovered in the section. Read this summary.You may not completely understandeverything in the summary at first. Whenyou finish working through the section,reread this summary. If you still do notunderstand something in the summary, askyour teacher for help.

    3. Rewrite the section headings andsubheadings as questions. Then look forthe answer to each question as you read.

    4. When you finish reading the text under aheading or subheading, think about whatyou have just read. Then write brief notesthat explain the key ideas discussed there.Try to do this without looking at the text.After you make your notes, go back to thetext you have just read. Add or change

    Using Your Textbook as a Study Toolanything you have just written to help youunderstand the text better.

    5. As you read each section, you willencounter Reading Checks. You should beable to answer these questions. If youcannot answer them correctly, go back andreview the material you just read.

    Using Your Textbook VisualsAs you read each page, look at anyphotographs, illustrations, or graphs thatappear on the page. Read the captions andlabels that accompany the photographs as wellas the titles of graphs. Think about theinformation each visual provides, and notehow it helps you to understand the ideaspresented in the text. For example, look closelyat the illustration on this page. Whatinformation does it convey to you?

    Water on Earth moves in an endless water cycle.

    Using the GlossaryNotice the terms that are in bold (dark, heavy)type. These terms are important words thatyou will need in order to understand and writeabout the information in each topic. Make surethat you understand these terms and how theyare used. Each boldfaced term appears in theGlossary at the back of this book.

    Science Skill 11

    BCS10_BM_F_3 6/9/08 12:37 PM Page 582

  • Science Skill 11 • MHR 583

    Using the Review QuestionsAt the end of every section, you will findreview questions under the heading CheckYour Understanding. At the end of everychapter, there are questions in the ChapterReview. If you are unable to answer thequestions at the end of the sections andchapters, reread the material to find theanswers. Ask your teacher to explain anythingyou still do not understand.

    Using Graphic OrganizersA good way to organize information you arelearning is to use a graphic organizer. Onekind of graphic organizer you will find useful isa concept map.

    Concept Map

    A concept map is a diagram that representsvisually how ideas are related. Because theconcept map shows the relationships amongconcepts, it can clarify the meaning of theideas and terms and help you to understandwhat you are studying.

    Study the construction of the concept mapbelow. Notice how some words are enclosedwhile others are written on connecting lines.The enclosed words are ideas or terms calledconcepts. The lines in the map show relatedconcepts, and the words written on themdescribe relationships between the concepts.

    As you learn more about a topic, yourconcept map will grow and change. There isno single “correct” concept map, there areonly the connections that make sense to you.Make your map as neat and clear as possible.Make sure you have reasons for suggesting theconnections between the concepts.

    When you have completed the concept map,you may have dozens of interesting ideas. Yourmap is a record of your thinking. Although itmay contain many of the same concepts as otherstudents’ maps, your ideas may be recorded andlinked differently. You can use your map forstudy and review. You can refer to it to help yourecall concepts and relationships. At a later date,you can use your map to see what you havelearned and how your ideas have changed.

    silverand gold

    appearance

    valuevalue

    two-dollarcoin

    CANADIAN COINS

    copper silver gold

    appearance appearance appearance

    value

    one-dollarcoin

    quarterdimenickelpenny

    value value value

    Instant Practice—Reading forInformation

    1. Go to the unit that your teacher tellsyou your class will be studying next.Scan the unit to predict the key ideasyou will be studying.

    2. In the first section of the unit, usestrategies 1 and 2 on the previous pagebefore you read the section.

    3. Read the first section of the unit usingstrategies 3 and 4 to make notes.

    BCS10_BM_F_3 6/9/08 12:37 PM Page 583

  • 584 MHR • Science Skill 11

    Flowchart

    A flowchart describes ideas in order. Inscience, a flowchart can be used to describe asequence of events, the steps in a procedure, orthe stages of a process. When making aflowchart, you must first find the one eventthat starts the sequence. This event is calledthe initiating event. You then find the nextevent and continue until you reach anoutcome. Here is a flowchart showing how ananimal fossil may be formed.

    Cycle Chart

    A cycle chart is a special type of flowchart. In acycle chart, the series of events do not producea final outcome. This type of chart has nobeginning and no end.

    To construct a cycle chart, you first decideon a starting point and then list eachimportant event in order. Since there is nooutcome and the last event relates back to thefirst event, the cycle repeats itself. Look at thecycle chart in the next column, which showschanges in the state of water.

    Spider Map

    A spider map is a concept map that you mayfind useful for brainstorming. You may, forexample, have a central idea and a jumble ofassociated concepts, but they may notnecessarily be related to each other. By placingthese associated ideas outside the mainconcept, you can begin to group these ideas sothat their relationships become easier tounderstand. Examine the following spider mapof the geological time scale to see how variousconcepts related to this time scale may begrouped to provide clearer understanding.

    solid

    gas

    liquid liquidChanges inthe stateof water

    An animal dies.

    Scavengers consume most of the body.

    Bacteria cause soft parts of the body to decay.

    A solution of water and minerals flows through the bones.

    The water dissolves the calcium in the bones.

    The minerals take the place of the calcium.

    A hard, rocklike fossil is formed.

    few rocks

    ice ages

    Precambrian

    MesozoicC

    enoz

    oic

    Paleo

    zoicbacteria

    age of mammals

    1st time span

    4th time span

    AppalachianMountains

    trilobites, brachiopods

    Rocky Mountains

    age of dinosaurs

    2nd time span

    3rd time span

    GEOLOGICAL TIME SCALE

    BCS10_BM_F_3 6/9/08 12:37 PM Page 584

  • Science Skill 11 • MHR 585

    Venn Diagram

    Comparing and contrasting information isanother way to help solidify your learning.When you compare, you look for similaritiesbetween two concepts or objects. When youcontrast, you look for differences. You can dothis by listing ways in which two things aresimilar and ways in which they are different.You can also use a graphic organizer called aVenn diagram to do this, using two circles.

    Example

    Similarities DifferencesDifferences

    Plants• make their

    own food• remain in

    one place

    • living• made

    of cells

    Animals• must find food• move from

    place to place

    Instant Practice—Graphic Organizers

    1. Create a concept map with the word“motion” at the centre. Include thefollowing terms: uniform motion,acceleration, average speed, averagevelocity, displacement, distance, �d ��t, �v � �t. Show how each term isconnected to motion and to the otherterms.

    2. Create a flowchart that takes youthrough all the steps involved in makinga peanut butter and jelly sandwich.

    3. Design a spider map with the centraltheme of climate change.

    4. Create a Venn diagram in which youcompare and contrast one of thefollowing pairs.(a) car and bicycle(b) fission and fusion(c) tropical rainforest and temperate

    rainforest

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  • 586 MHR • Science Skill 12

    Throughout history, people have developed systems of numbering and measurement.When different groups of people began tocommunicate with each other, they discoveredthat their systems and units of measurementwere different. Some groups within societiescreated their own unique systems ofmeasurement.

    Today, scientists around the world use themetric system of numbers and units. Themetric system is the official system ofmeasurement in Canada.

    The Metric SystemThe metric system is based on multiples of 10. For example, the basic unit of length is themetre. All larger units of length are expressedin units based on metres multiplied by 10,100, 1000, or more. Smaller units of lengthare expressed in units based on metres dividedby 10, 100, 1000, or more.

    Each multiple of 10 has its own prefix (aword joined to the beginning of anotherword). For example, “kilo-” means multipliedby 1000. Thus, one kilometre is 1000 metres.

    1 km � 1000 m

    The prefix “milli-” means divided by 1000.Thus, one millimetre is one-thousandth of a metre.

    1 mm � m

    In the metric system, the same prefixes areused for nearly all types of measure, such asmass, weight, area, and energy. A table of themost common metric prefixes is given at thetop of the next column.

    Example 1

    The distance from Penticton to Prince Rupertis 1431 km. Express this distance in metres.

    Solution1431 km � ? m

    1 km � 1000 m1431 km � 1431 � 1000 m

    � 1 431 000 m

    Example 2

    There are 250 g of cereal in a package. Expressthis mass in kilograms.

    Solution1 kg � 1000 g

    250 g � 4 � 1000 g

    g � 250 g

    kg � 0.25 kg

    The next table lists most of the frequently usedmetric quantities you will encounter in yourscience classes.

    Units of Measurement and Scientific Notation

    Science Skill 12

    SymbolPrefixes Relationship to the Base Unit

    giga-

    mega-

    kilo-

    hecto-

    deca-

    deci-

    centi-

    milli-

    micro-

    nano-

    Commonly Used Metric Prefixes

    G

    M

    k

    h

    da

    d

    c

    m

    n

    109

    106

    103

    102

    101

    100

    10–1

    10–2

    10–3

    10–6

    10–9

    = 1 000 000 000

    = 1 000 000

    = 1 000

    = 100

    = 10

    = 1

    = 0.1

    = 0.01

    = 0.001

    = 0.000 001

    = 0.000 000 001

    14

    11000 1000

    4

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  • Science Skill 12 • MHR 587

    SI UnitsIn science classes, you will often be instructedto report your measurements and answers in SIunits. The term SI is taken from the Frenchname Le Système international d’unités. In SI,the unit of mass is the kilogram, the unit oflength is the metre, the unit of time is thesecond, the unit of temperature is the kelvin,and the unit of electric current is the ampere.Nearly all other units are defined ascombinations of these units.

    Example 1

    Convert 527 cm to SI units.

    SolutionThe SI unit of length is the metre.1 m � 100 cm

    Example 2

    Convert 3.2 h to SI units.

    SolutionThe SI unit of time is the second.1 min � 60 s; 1 h � 60 min

    Frequently Used Scientific Quantities, Units, and Symbols

    UnitQuantity Symbol

    nanometremicrometremillimetrecentimetremetrekilometre

    Length nm�mmmcmmkm

    Mass

    gramkilogramtonne

    gkgt

    Area square centimetresquare metrehectare

    cm2

    m2

    ha

    Volume cubic centimetrecubic metremillilitrelitre

    cm3

    m3

    mLL

    Time second s

    Temperature degree Celsius ºCForce newton N

    Electric current ampere A

    Quantity of electric charge

    coulomb C

    FrequencyElectrical resistance

    hertzohm

    Hz�

    Power watt W

    Energy joulekilojoule

    JkJ

    Pressure pascalkilopascal

    PakPa

    Instant Practice—Using MetricMeasurements

    1. A container holds 250 mL of juice.Express the volume in L.

    2. A hockey puck has a mass of 160 g.What is the puck’s mass in kg?

    3. The average length of a person’s foot is0.265 m. What is this length in cm?

    4. You walk 1.2 km to school. Express thisdistance in m.

    5. A student adds 0.0035 L of acid towater. Express the volume in mL.

    6. A hamburger contains 23 g of fat.Express the mass in mg.

    527 cm × 1 m100 cm =