1. Methods of Science
Chapter 1.3 pages 16-21

2. The Scientific Method: Steps used to gather data and answer questions.

3. The Scientific Method
The scientific method generally follows a pattern:
Ask a question
Make observations
Form a Hypothesis
Experiment
Collect and analyze data
Draw conclusions

4. 1. Ask A Question and 2. Make an Observation
Scientific inquiry begins with observation. Observation is the act of noting or perceiving objects or events using the 5 senses.
Combining your observation with your past knowledge allows you to make inferences, or logical conclusions.

5. Observation vs. Inferences
Inferences are an explanation for an observation that you have made.
Inferences often change when new observations are made.
Observation: The grass is wet.
Inferences: It rained. OR
The sprinklers went off.

6. 3. Hypothesis
A hypothesis is a TESTABLE explanation for your question.
This statement can be tested by additional observations or experimentation.
An educated guess based on what is already known
Usually written as an “If/then”
statement.

7. 4. Experiment Experiment – a planned procedure to test a hypothesis.
Controlled experiment – an experiment where an experimental group is compared to a control group.
Control group is a group in an experiment that receives no experimental treatment.
An experimental group is the group exposed to the factor being tested.

8. Experimental Design
Both control and experimental groups are designed to be identical except for one variable.
Variables - factors, conditions, and/or relationships that can change or be changed in an event or system.

9. Three kinds of variables in a scientific investigation:
The factor that is varied/changed in an experiment is called the independent variable.
The variable that is measured in an experiment is called the dependent variable.
A constant is a factor that remains fixed during an experiment.

10. Memory Trick D R Y M I X Dependent Manipulated Responding Independent
Y-axis
Manipulated
Independent
X-axis
What were the independent and dependent variables for our paper towel lab?

11. Identifying and Manipulating Variables
Example: A student wanted to test how the mass
of a paper airplane affected the distance it
would fly. Paper clips were added before each
test flight. As each paper clip was added, the
plane was tested to determine how far it would
fly.
Independent variable – the mass of the
plane based on the number of paper clips added.
Dependent variable – the distance flown.
Controlled variable – the fact that the same plane
was used for each trial.

12. 5. Collect Data Data is any information gained from observations.
2 types:
Quantitative – measureable or countable
3 meters long
4 marbles
50 kilograms
35 degrees Celsius
Qualitative – describable, not measureable
red flowers
smells like fresh baked cookies
Tastes bitter

13. 6. Analyze Data A graph of the data makes the pattern easier to grasp.
On a graph, the x axis represents the independent variable
the y axis represents the dependent variable

14. Identify the independent and dependent variables
in each example below and label the graph:
Human heart rate will
increase from sitting
to standing.
2. I have 3 different types of
paper towels; I think type A
will hold the most water.
amt of
water
heart rate
body position
type of paper
towel
3. Adding sugar to water will
increase the temperature
at which water boils.
4. The warmer an egg,
the faster it will open.
time
temp
temp
amt of sugar

15. 7. Conclusion
Once data are collected and analyzed, a hypothesis is either supported or rejected.
Even when a hypothesis has not been supported, it is valuable.
A hypothesis can be supported, but never proven because another experiment with new data can alter the conclusion.
Publication
Scientists often publish the results of their experiments for review and use by other scientists.

16. Form a Hypothesis
Hypothesis: an testable statement or prediction; an “if, then” statement
If ____independent variable______
then__dependent variable_______

17. Example: Independent Variable: I feed my cat a lot of food
she will get fat
If ___________________________
then _________________________

18. Try to use INCREASE and DECREASE in your hypothesis!
Remember
Try to use INCREASE and DECREASE in your hypothesis!
Ex. IF I increase the amount of food I give my cat, THEN she will increase her weight

19. Use this hypothesis to identify the variables:
Practice
Use this hypothesis to identify the variables:
If I leave all the lights on all day,
then my electric bill will be expensive
IV: ______________________
DV: ______________________

20. If I brush my cat more, then there will be less fur on my furniture
IV: ______________________
DV: ______________________

21. Now read the following experiment and identify the independent and dependent 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 a oven that was turned on low heat. She then measured how rotten the milk was after 10 days.
IV: ____________________________________
DV: ____________________________________