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Scientific Measurement and Process

Essential Questions

How are the attributes (characteristics) of an object measured?

Why is it important to use a common set of standards (units)?

How do you conduct an experiment and communicate the results?

Name __________________________

Period ______

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Measurement Unit Enduring Learning Standards of measurement are used by society to ensure quality and consistency. Essential Questions What makes a safe laboratory? How are the attributes (characteristics) of an object measured? Why is it important to use a common set of standards (units)? Objectives Students will know: -types of variables that can be controlled. -different ways to display data. -lab safety procedures. -how to present and display the investigation. -difference between qualitative and quantitative data. - the difference between control, dependent, and independent variables Students will be able to: -exhibit safe laboratory practices during investigations. -accurately use general terms of science. -accurately measure length, mass, volume, and temperature using appropriate equipment and metric units. -construct and interpret tables and graphs to represent data. -identify questions and concepts that guide scientific investigations. -formulate and revise explanations and models using logic and evidence. - recognize and analyze alternative explanations and models. - conduct a scientific investigation and report the results and implications

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PA Standards Addressed Standard - 3.1.7.A9:

• Understand how theories are developed. • Identify questions that can be answered through scientific investigations and

evaluate the appropriateness of questions. • Design and conduct a scientific investigation and understand that current

scientific knowledge guides scientific investigations. • Describe relationships using inference and prediction. • Use appropriate tools and technologies to gather, analyze, and interpret data

and understand that it enhances accuracy and allows scientists to analyze and quantify results of investigations.

• Develop descriptions, explanations, and models using evidence and understand that these emphasize evidence, have logically consistent arguments, and are based on scientific principles, models, and theories.

• Analyze alternative explanations and understanding that science advances through legitimate skepticism.

• Use mathematics in all aspects of scientific inquiry. • Understand that scientific investigations may result in new ideas for study, new

methods, or procedures for an investigation or new technologies to improve data collection.

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Definition Sheet

Accuracy ____________________________________________________________ _____________________________________________________________________ Adhesive ____________________________________________________________ _____________________________________________________________________ Cohesive ____________________________________________________________ _____________________________________________________________________ Density _____________________________________________________________ _____________________________________________________________________ Derived _____________________________________________________________ _____________________________________________________________________ Gram _______________________________________________________________ _____________________________________________________________________ Liter ________________________________________________________________ _____________________________________________________________________ Mass _______________________________________________________________ _____________________________________________________________________ Matter ______________________________________________________________ _____________________________________________________________________ Meniscus ___________________________________________________________ _____________________________________________________________________ Meter ______________________________________________________________ _____________________________________________________________________

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Precision ____________________________________________________________ _____________________________________________________________________ Second _____________________________________________________________ _____________________________________________________________________ Standard ____________________________________________________________ _____________________________________________________________________ Volume _____________________________________________________________ _____________________________________________________________________ Weight ______________________________________________________________ _____________________________________________________________________

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Prefixes used in the Metric System kilo

hecto deka meter deci centi milli

Functions of Measurement

Type of Measurement

What it Measures? Measuring Device Standard Unit

distance volume density

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The Need for Standards of Measurement Purpose:

The purpose of this lab is to investigate the reliability of nonstandard measurement devices such as hands, feet, and arm spans.

Procedure:

Using the unit on the left of the chart, measure the object on the right. If the answer is less than one, use fractions or decimals to express your answer.

Using Measure Answer hand width lab table width hand length lab table length foot length height of the table arm span width of room

Using Measure Answer width of paper lab table width length of pen lab table length length of paper height of the table width of floor tile width of room

Why is it that the answers in the first chart varied form person to person and the answers in the second were very close? If you were buying rope and you had to pay for it according to hand length, whose hand would you want to use? Why?

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Introduction to Distance Measurement

Purpose

The purpose of this laboratory is to practice estimation skills and the use of measuring devices such as meter sticks for measuring length. The conversion of units will also be practiced during the write-up of the laboratory report.

Materials: meter stick notebook pen/pencil Procedure:

1. Gather materials. 2. Estimate the dimensions of the objects in the list below. All measurements should be recorded in the unit which makes the most sense. (millimeters, centimeters, or meters) 3. Measure and record the list of items below. All measurements should be recorded in the unit which makes the most sense. (millimeters, centimeters, or meters) All items are to be measured to the nearest one millimeter.

List of Items to be Measured: 1. Width of Lab Table 6. Length of Binder 2. Width of Binder 7. Width of One Block of Floor Tile 3. Length of Front Lab Desk 8. Width of Front Lab Desk 4. Length of Eraser 9. Width of Eraser 5. Height of Eraser 10. Your Height New Terms:

Accuracy - how close to the correct measurement Precision - the size of the unit to which an object is measured

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Example...

If an object was found to measure 9 meters, 31 centimeters, and 5 millimeters in length, the measurement could be written as: 9.315 meters OR 931.5 centimeters OR 9315 millimeters All are correct, and all have the same precision.

Lab Write-Up In a data table, list the objects measured, estimates of their dimensions and their actual measurements.

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Data Table Object Estimated

Measurement Actual

Measurement

Conclusion

Using the proper measuring device, it is possible to obtain accurate, precise measurements of specified objects using the metric system. Explain.

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Mass Lab

Purpose: The purpose of this laboratory is to practice the use of mass measurement devices and metric units. Graphing will also be reinforced upon the completion of this lab. Materials: Notebook Lab Instruction Sheet Thirty Paper clips Thirty Craft Sticks Triple Beam balance Graph Paper Colored Pencils Ruler Background:

Anything that is not energy is made of something called matter. This matter takes up space and has mass. Mass is a measure of the amount of matter an object contains. Many people confuse how much mass something has with how much space it occupies. Think of it this way. . . if you have a gallon jug full of air, it isnʼt very heavy at all. If you fill it with lead, it will be much heavier (more mass) than when it is filled with air (less mass). Mass and weight are NOT the same. We often talk about them as very similar because they are related and also because most of us do not leave the earthʼs surface most of the time. We will talk about the relationship between mass and weight later in class.

Procedure: 1. Gather your materials. 2. Find the mass of 5 paper clips. Donʼt forget to zero the balance first. 3. Record the mass in the data table below. 4. Repeat steps 2 and 3 for 10 paper clips, 20 paper clips, and 30 paper clips. 5. Repeat steps 2, 3, and 4 using craft sticks. Object Mass

5 Paper Clips

10 Paper Clips

20 Paper Clips

30 Paper Clips

Object Mass

5 Craft Sticks

10 Craft Sticks

20 Craft Sticks

30 Craft Sticks

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When you have obtained all of the data from the lab investigation, get a piece of graph paper from the front of the room. Before you make a graph of your information, consider the space you have on the paper and the information you need to display. On the vertical axis your units should be _______________________ . On the vertical axis, you should start with the number ________ and end with the number _______ . This gives a range of ________. On the horizontal axis your units should be _____________________ . On the horizontal axis, you should start with the number ________ and end with the number ________ . This gives a range of ________ . Now, construct a graph of the number of items vs the mass of the items. Right now only plot the points. DO NOT CONNECT THE POINTS. After you have plotted the points your see your teacher for help to construct a “Line of Best Fit” through the points. This line should be straight. It may not actually hit every point you have plotted, but it should come near to most of them and extend through the end of the graph. What do you think this line would represent? How much mass would zero craft sticks have? When you have plotted all of the points for the paper clips, you should do a second plot for the craft sticks. Do this on the same graph. Construct a line of best fit as you were instructed for the other plot. Make sure you use a different color for each of the two separate lines and include a key to the colors on the graph.

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From the graph, you should be able to predict the mass of amounts other than those you directly measured. In the chart below, record what the masses should be for 8, 13, 17, 22, 26, and 28 items

When you have estimated the mass from the graph, measure the actual mass of these items. You should then answer the questions on the back of this page.

Object Estimated Mass Actual Mass 8 Paper clips

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17

22

Object Estimated Mass Actual Mass 8 Craft Sticks

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17

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1. Place a point (not an X) on the graph for each of the actual masses found in this second part of the lab.

2. Were the actual mass measurements the exactly the same as the estimated masses from the graph? If they were not, explain what factors might have influenced the difference.

3. Is there an advantage to using the graphing method for determining the mass of the items rather than actually measuring the items? Do you think that the advantages out weigh the disadvantages? Explain your answers.

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Taking up Space

A Lab on Volume

Volume is the amount of space an object occupies. Liquid volume can be measured accurately using a device called a graduated cylinder. The standard unit for volume is the liter. A liter is slightly more than a quart in the English system of measurement. When using smaller volumes, the common unit is the milliliter. The purpose of this lab is to gain experience reading graduated cylinders and measuring with graduated cylinders. When most liquids are placed in a container such as a graduated cylinder, the liquid forms a downward curve. This curve is called a meniscus. It is caused by a property of the liquid called adhesion. To read the volume accurately, read the volume at the bottom of the curve. (See the example below.) Some liquids, such as mercury, are cohesive and form a curve just the opposite of water. Materials Graduated Cylinders- Various sizes Water Notebook Pen/Pencil Procedure 1. Gather Materials. 2. Read the volume on the graduated cylinders at your table. Record the volumes in a data table in your notebook. When the teacher tells you to do so, switch tables with another group. Read the graduated cylinders at this new table. 3. At each table, read and record the following… Cylinder Size, Degree of Refinement, and the Volume of the Sample. 4. Clean up your area.

Volume Lab Data Sheet

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Cylinder Number Cylinder Size Degree of

Refinement Volume of Sample

1

2

3

4

5

6

7

8

9

10

11

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Volume of Irregularly-Shaped Objects

Background The amount of space an object occupies is its volume. If you were to fill a cup with water, the water would take up all the available space inside the cup. If you place some marbles inside of paper cup instead, they will take up some of the space, but still leave some “empty.” What would happen if you filled the cup with water and then added the marbles ? Any object, no matter how big or small has volume. In the metric system, the standard unit of volume is the liter. Dividing the liter into 1000 equal parts gives us units called milliliters. Imagine a cube like the one drawn below; the length of each side is 1 centimeter. The volume of this cube would be 1 cubic centimeter. This can also be written as 1 cc or 1 cm3.

To find the volume of any rectangular or square cube, you use the formula:

Volume = length x width x height A block with a volume of 1 cubic centimeter occupies a volume of 1 milliliter. The two measurements are exactly the same ! Usually, we use the cubic centimeter when referring to solids and the milliliter when talking about liquids and gases. Finding the volume of other shapes isnʼt too much harder, you just have to know the right formula to use. Finding the the volume of irregularly shaped objects like rocks, keys, or any object with holes is a different process. This process is similar to the situation described above with the marbles and cup of water. To find the volume of these, we use a process called displacement. To displace is to move something out of the way. There are two main ways to do this. One way is to use an overflow can. This can is filled with water and then the object is placed into the can. The

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water that is pushed out is caught and its volume is measured. This volume is the same as the volume of the object. A second method for finding the volume of irregularly shaped objects by displacement is by using a graduated cylinder. To do this, you will place between 20 and 40 milliliters of water in a graduated cylinder (depending on the size of the cylinder). You then need to accurately record how much water is in the cylinder. Now, GENTLY lower the object into the water using the string. Why is it important to lower the sample in so gently ?

What will happen to the level of the water ? Often, we tie a string around the object whose volume you are trying to find so that we donʼt break the cylinder and for another reason that you may have described above. Read the new volume in the graduated cylinder. The difference between this volume and the original is the volume of the object. Why wouldnʼt a graduated cylinder work with all objects you might measure ? Procedure: In todayʼs lab you are going to find the volume of several materials by the process of displacement. Using the process described in the background of the lab, find the volume of a piece of each of the three materials. Record your data in the table on the next page. Repeat the process for each sample. Use 2 pieces of rock for each trial.

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Data

Object: Trial One Trial Two

Volume of Sample and Water Volume of Water

Difference in Volume

Volume of Sample

Object: Trial One Trial Two

Volume of Sample and Water Volume of Water

Difference in Volume

Volume of Sample

Object: Trial One Trial Two

Volume of Sample and Water Volume of Water

Difference in Volume

Volume of Sample

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Summary Questions How could you find the volume of your own body ? How many milliliters are in a 2-liter bottle ? If you were given a bucket of limestone gravel, how could you find the volume of the space still available in the bucket ? What is the volume of dirt in a hole measuring 125 cm x 86 cm x 1452 cm ? Show your work.

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What Are You...Dense? A Laboratory that Has Mass and Takes up Space

Background:

Density is a property of matter that describes how tightly packed the particles are that make up the material. Scientifically, it is the mass per unit of volume. Mass is commonly measured in grams. Volume is usually measured in cubic centimeters (cm3) for solid objects and milliliters (ml) for liquids. One cubic centimeter and one milliliter are exactly the same amount.

Purpose

The purpose of this lab is to practice finding the density of a variety of objects. Volume of cubic, regularly shaped objects can be found by multiplying the length times the width times the height. Density can be found by dividing the mass of the object by its volume.

Brass Iron Aluminum Wood Mass

Length

Width

Height

Volume

Density

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Density Practice Problems

d = m / v m = v x d v = m / d

1. A brick has a mass of 250 grams and a volume of 50 ml. What is its density? 2. A ball has a volume of 1250 ml and a mass of 125 g. What is its density? 3. A brick with a volume of 750 ml has a density of 5 g/ml. What is its mass? 4. A block with a density of 7.5 g/ml has a volume of 15 ml. What is its mass? 5. A box has a mass of 4000 g and a density of 20 g/ml. What is its volume? 6. A 350 g object has a density of 7 g/ml. What is its volume?

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The Great Grow Along Dear Parent and/or Guardian, Next week your child will be beginning a class project called The Great Grow Along: A tail of two rats and you! Students will be examining the growth and health of six rats over a four week period. They will learn how the scientific method is used in scientific investigations, and how nutrition affects growth. As part of the project, students will feed female albino rats identical diets (cereals, vegetables, and meat) for four weeks. However, the liquid the rats will receive will differ. One rat will be given whole milk to drink while the other is given sweetened water. (We actually have three sets of rats, three will be fed milk and the other three will be fed sweetened water.) Students will learn the importance of controls and variables in experiments, how to make accurate observations, how to record and display data, and how to analyze and draw conclusions from data. During the project, each rat will need to be cared for on weekends. This involves feeding the rat according to instructions that students will receive in class. If your child would like to take care of a rat for a weekend, and YOU are willing to have the animal in your home, please contact me at school via email. I hope you and your child enjoy The Great Grow Along! Sincerely, 7th Grade Science Teachers

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NAME____________________________ PER._____SCORE = _____/60 OTHER GROUP MEMBERS___________________________________ SCIENCE EXPERIMENT FORM INVESTIGABLE QUESTION IDENTIFY VARIABLES FOR THE EXPERIMENT INDEPENDENT VARIABLE (factor you changed)

DEPENDENT VARIABLE (factor that changed due to Independent Variable) CONTROLLED VARIABLES (identify the factors you plan to keep the same in your test) HYPOTHESIS (identify what you predict will happen to the dependent variable as the independent variable

changes) EXPERIMENT PLAN (1. List materials; 2. Detailed step by step directions for your investigation)

RESULTS (Attach one or more separate sheets of: observations, data tables, and graphs.

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CONCLUSION/EXPLANATION (The teacher may give you one or more specific questions to answer in complete

sentences. The conclusion should refer to the hypothesis and use the results to give a reasonable explanation of what happened in the

experiment.) RUBRIC: For each item listed, an evaluation will be made on the following scale…

10= EXCELLENT. Work demonstrates a high degree of thought, effort and attention to instructions. 8= ACCEPTABLE. Work demonstrates thought and effort. Some room for improvement. 6=NEEDS WORK. Work shows some promise, but lacks sufficient detail or effort shown in acceptable work. 4=MINIMAL EFFORT. Little or no thought or effort. Incomplete or unfinished. Unacceptable. 0=Not attempted. 10 8 6 4 0 QUESTION, VARIABLES AND HYPOTHESIS Clear and investigable QUESTION. Not a “How” or “Why” question. Reading the question leads logically to an experiment to answer the question. Variables are correctly identified for the experiment. All necessary variables that could have an effect on the outcome are controlled Hypothesis discusses how the dependent variable will vary with the independent variable. 10 8 6 4 0 EXPERIMENT PLAN The plan is detailed and easy for the reader to follow. The procedures are safe, ethical and doable with available materials. Specific materials are identified on the first two lines. Procedure is recorded as numbered steps. 10 8 6 4 0 RESULTS Observations are specific and clear statements of fact and avoid assumptions and inferences. Includes qualitative and quantitative results when appropriate. Data tables are logically organized, clearly labeled and units of measure are specified. Graphs are included when necessary. 10 8 6 4 0 CONCLUSIONS and EXPLANATIONS Results are used and referred to in conclusions. Explanations are reasonable and do not contradict results. Errors in the experiment are addressed with possible solutions proposed. Needs for further investigation are addressed 10 8 6 4 0 QUALITY OF WRITING Answers express complete thoughts and are written in complete sentences. Writing is done in impersonal tone and avoids the use of “I” and “WE”. Plan is detailed and avoids the use of “it” and “they”. 10 8 6 4 0 NEATNESS Work is neat and legible.

Evidence of effort to follow all directions and present a high

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How to Write a Conclusion The following questions should be addressed. This does not mean answered in a list format. • What does the data indicate?

(Hints- Compare the end mass of the Milk Rats and Sugar Water Rats - Look at Day ____. Explain why the lines on the graph change after this day. Remember to use the actually measurements.)

• How do the results compare to the hypothesis?

(Hint- Did the results match what you predicted in the hypothesis?)

• Where are the problems with the investigation? (Hint- Think about all the things that we listed in the control variables that should have been equal for all the rats. Did anything happen that made some of these things different for the rats?)

• How could the experiment it be improved? (Hint-Tell me how you could fix the problems you listed above)

• How confident are you with the results? (Hint- Did the problems out weight the results or were the problems minor? This is a judgment call. You will need to support your position.

• What is the significance of your findings?

(Hint- Rats and People are different, but we are similar in what we need to survive and grow. Can we use what we learned from the rats to help people?)

Remember that it is crucial for your discussion to rest firmly on the results, so they should be referred to in your discussion. The key is to refer to them and relate them to the point that you are trying to make. Donʼt simply repeat the results!

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7 Guidelines for Scientific Writing

1. All scientific names (genus and species) must be italicized. 2. Use the metric system of measurements. Abbreviations of units are used without a following period. 3. Numbers should be written as numerals when they are associated with measurements.

example, 6 mm or 2 g

4. Avoid using the first person, I or we, in writing. Keep your writing impersonal, in the third person. Instead of saying, "We weighed the frogs and put them in a glass jar," write, "The frogs were weighed and put in a glass jar." 5. Avoid the use of slang and the overuse of contractions. 6. Be consistent in the use of tense throughout a paragraph--do not switch between past and present. It is best to use past tense. 7. Be sure that pronouns refer to antecedents. For example, in the statement, "Sometimes caterpillars are in cherry trees but they are hard to find,"

Does "they" refer to caterpillars or trees?