Scientific Evaluation

Being Objective

Measurements

0Taking accurate measurements is only one aspect of scientific experiments

0When recording measurements, be sure to list the units

0 Important to indicate whether you measured in metric or English units

The Metric System0How the world communicates the results of its

experiments0Decimal system of measurement0All units divisible by 10

Base Units

0Most common base units used in the metric system0 Gram (g)0 Meter (m)0 Liter (L)0 Second (s)0 Celsius degree (°C)

0All other units in metric system derived from these base units

Prefixes

0Kilo (x1000) [k]0Hecto (x100) [h]0Deka (x10) [D]0BASE UNITS (x1)0Deci (x0.1) [d]0Centi (x0.01) [c]0Milli (x0.001) [m]

Now make a mnemonic device for the metric

prefixes using the letters in red

Putting it all together…

0Kilosecond (ks = 1000 seconds)0Hectometer 0Centigram 0Dekasecond 0Deciliter 0Kilometer 0Milligram

(hm = 100 meters)

(cg = .01 gram)

(Ds = 10 seconds)

(dL = .1 liter)(km = 1000 meters)

(mg = .001 gram)

“m”

How can we tell whether an “m” stands for a meter or milli-?

0M at the end = meter0M at the beginning = milli0M by itself = meter

Practice

0400 millimeters in meters0 k h D (b) d c m0 4 0 00 =0.4 meters

05.27 kilograms in grams0k h D (b) d c m0 5.2 70 =5,270 grams

k h D (base) d c m

Practice

0Using your BYOT or iPads go to https://todaysmeet.com/andreskefsn

0Type your first & last name (no spaces) for the “nickname”

0Your message should include answers to the following:

1. 6.82 Dekaliters in deciliters2. 175 millimeters in hectometers3. 4 kilograms in centigrams

k h D (base) d c m

The Big Five1. Gram (g)- measurement of mass0Mass: a measure of the quantity of matter0Often confused with weight: the measure of force of

gravity between two objects0Equipment to measure mass

0 Triple beam balance0 Electronic balance

0Calibrate: adjust a measuring instrument to a standard0Tare: mass of the container, which is subtracted from the total

mass of the container and substance to find the mass of just the substance

Now it’s your turn…

0Complete “Balancing Chewing Gum” Experiment

The Big Five

2. Meter (m)- measurement of length0Length: the distance between two points0Equipment to measure length

0 ruler0 What if the object you need to measure is a potato?

3. Liter (L)- measurement of volume0Volume: the amount of space occupied by an object0Usually measure liquids by their volume0Be careful when measuring the meniscus: curve at the

surface of a liquid

The Big Five

Equipment to Measure Volume

Beaker: deep, wide-mouthed container with a pouring lip

Erlenmeyer flask: flat-bottomed, cone-shaped container

Graduated cylinder: tall container used to accurately measure the volume of liquids to the nearest milliliter

Buret: graduated glass tube with a control valve at the bottom

The Big Five

4. Second (s)- measurement of time0Critical to have someone act as a timer during

experiments0Record start and stop times using a clock/watch0Failure to accurately monitor time can make your

entire experiment invalid

5. Celsius degree (°C): is most commonly used unit of temperature0 Water freezes at 0°C0 Water boils at 100°C

0Temperature: a measure of heat intensity0The US still uses Fahrenheit scale for everyday

temperature measurements

The Big Five

Lab Experiment:

0 “Measuring the Volume of Irregularly Shaped Objects”0 How do you measure the volume of a biscuit?

0Once completed with the lab..0 Work on “Metric Units” worksheet

Scientific MethodAn organized approach to solving problems

1. ASK QUESTIONS2. DEFINE THE PROBLEM3. CONDUCT RESEARCH4. STATE THE HYPOTHESIS5. DESIGN THE EXPERIMENT6. CONDUCT THE EXPERIMENT7. EVALUATE THE RESULTS8. REPORT THE RESULTS

Steps in the Scientific Method1. ASK QUESTIONS

0 Why are you interested?0 What are the benefits of investigating this topic?0 How can this be analyzed?

0 For example, the Best Bean Company’s navy bean crop was destroyed by plant disease this year.0 Is there a substitute for navy beans that will be comparable

in flavor, texture, color, and cost?

Steps in the Scientific Method2. DEFINE THE PROBLEM

0 What is the exact purpose of your specific experiment?0 In class, problem = purpose for experiment0 Ex: To find a substitute bean similar in color, shape,

texture, flavor, cooking characteristics, and cost, as well as its’ impact of customer approval

Steps in the Scientific Method3. CONDUCT RESEARCH

0 List possible causes of your problem0 Books, articles, online sources

0Referred to as “Review of Literature”0 Check information on related studies0 Ex: finding names and descriptions of different kinds of

beans or looks for recipes using other types of beans

Steps in the Scientific Method

4. STATE THE HYPOTHESIS0 Hypothesis:

0A possible solution to the problem0an educated guess or prediction0An “if, then” statement

0 Ex: Greater northern beans, pink beans, and pinto beans are acceptable substitutes of navy beans.

Steps in the Scientific Method

5. DESIGN THE EXPERIMENT0 Variables:

0 Factor that is being changed0 Ex: kind of bean

0 Control:0 Standard against which you measure all changes0 Ex: navy bean

0 Variation:0 Change you made in the experiment0 3 variations (greater northern, pink, and pinto beans)

TYPES OF VARIABLES

0 Independent Variable0 The variable that is changed by the scientists0 The “I control” variable

0Dependent Variable0 The variable that might change because of what the

scientist changes0 What is being measured

Remember!

Your hypothesis can TELL you what your variables are!

Example: If I drink Mountain Dew before bed, then I will not sleep very much.

0 IV: Drinking Mountain Dew0 DV: the amount of sleep

Practice

Use this hypothesis to identify the variables:

If I consume a large amount of sodium, then my body will dehydrate more quickly.

0 IV:___________________________________________0 DV:__________________________________________

Practice

Use this hypothesis to identify the variables:

If I brush my teeth more, then there will be less plaque build-up on my teeth.

0 IV:___________________________________________0 DV:__________________________________________

Practice

Now read the experiment and identify the variables:

Elizabeth wanted to test if temperature affected how fast milk goes bad and curdles. She left milk in a room temperature closet, a fridge, and an oven that was turned on low heat. She then measured how rotten the milk was after 10 days.

0 IV:___________________________________________0 DV:__________________________________________

Going back to your hypothesis..

0Hypothesis: an educated guess or prediction; an “if, then” statement

If _____independent variable _____then _____dependent variable_____

Example:

Independent Variable:I feed my cat a lot of food

Dependent Variable:her weight will increase

If ______________________________then ______________________________

Remember!

Try to use INCREASE and DECREASE in your hypothesis!

Example: IF I increase the amount of water I drink, THEN I will increase the efficiency of my kidneys.

Steps in the Scientific Method

6. CONDUCT THE EXPERIMENT0 In class, groups will often conduct different variations

SO…..0 Follow experiment directions EXACTLY in order to

ensure accurate data

Steps in the Scientific Method

DATA COLLECTION0Numerical Observations:

0 i.e. Quantitative Observations0 Still require units and descriptions or the numbers

won’t make sense (time, temperature, mass, etc)0Descriptive Observations:

0 i.e. Qualitative Observations0 Factors such as color, texture, temperature, and odor

Steps in the Scientific Method

7. EVALUATE THE RESULTS0 Read data, observations, and notes0 Look for patterns, common factors, changes, and

questions0 Look for answers to the questions and support

for/against your hypothesis

Steps in the Scientific Method

8. REPORT THE RESULTS0 Form a CONCLUSION that analyzes and applies data0 Answers how, what, where, when, or why0 Many experiments may lead you to more than one

conclusions OR more than one option to solve your problem0State ideas for further research

0 Lab reports

Now try it on your own!

0Complete worksheet “A Variable Way to Practice Variables”

Assignment: The Twinkie Project

0Using the steps of the scientific method, create a hypothesis about Twinkies