1. Unit 1: The Scientific Method Chapter 1-1 & 1-2

2. Scientific Method
The scientific method is a problem-solving procedure used by scientists to seek answers to questions.

3. Scientific Method 1. Identify a Problem 2. Create a Hypothesis
3. Design and perform an experiment.
4. Record Data and Analyze
5. State a Conclusion
6. Check for sources of error

4. 1. Identify a Problem
Observations are descriptions about the way something is or the way things happen
From these observations, a question is formed about why or how

5. Checking for understanding
Barney observes:
When I drink Coke, I burp a lot.
What is a question that Barney can ask Professor Frink?

6. 2. Create a Hypothesis A Hypothesis is a prediction that can be tested
Should be written in the form of an
“If…, then…” statement

7. Checking for understanding
If people ______________,
then they will ______ more.
Can this hypothesis tested?

8. Hypothesis vs. Theory
Hypothesis: a prediction that can be tested and may or may not be true
Theory: a well-tested explanation that is supported by many types of evidence.
In science, theories are nearly facts
Ex. Theory of Evolution,
Theory of Relativity,
Cell Theory

9. 3. Controlled Experiment
Hypothesis is tested
Procedure—the steps followed during an experiment
Controlled experiments have experimental group(s) & a control group

10. Example:
Professor Frink wants to determine if Coke will increase the frequency of burping.
He gives 10 volunteers (subjects) from Springfield Coke and another 10 subjects water. All other conditions are kept the same.
All people are years old
All people are healthy.
All people have to not eat or drink for 3 hours before the experiment.

11. Subject

12. Variable: anything that can influence the outcome of the experiment
Control Group: group where all variables are kept the same
Used as “normal” for comparison
Experimental Group: group(s) where all the variables are the same except the one variable being tested

13. Checking for understanding
Professor Frink gives 10 volunteers (subjects) from Springfield Coke and another 10 subjects water.
All people are years old
All people are healthy.
All people have to not eat or drink for 3 hours before the experiment
Which group is the control group?
Which group is the experimental group?
What are the variables that are being controlled?

14. Independent Variable: What is being tested
The variable that is changed
Dependent Variable: What is measured or observed
The variable that changes because of the independent variable

15. Checking for understanding
If people drink Coke, then they will burp more.
Professor Frink gives 10 volunteers (subjects) from Springfield Coke and another 10 subjects water.
What is the independent variable?
What is the dependent variable?

16. If people drink Coke (independent variable),
then they will burp more (dependent variable).

17. 4. Record Data & Analyze Collect & record Data (information)
Data can be recorded in a table
Analyze the data by graphing it
Bar graphs: show comparisons
Line graphs: show changes over time

18. Experimental Group: Coke
Example:
Average # of Burps
Control Group: Water 2
Experimental Group: Coke 6
Dependent Variable: what you measure
Independent Variable
Control

19. Example: Average Number of Burps for Water vs. Coke
Proper units
Title
Average Number of Burps for Water vs. Coke
Y-axis = Dependent Variable
Type of Beverage
X-axis = Independent Variable
Label

20. 5. Conclusions
If the results are in agreement with the hypothesis then the hypothesis is “accepted”.
If the results disagree with the hypothesis then the hypothesis is “rejected”

21. Checking for understanding
In the example is the hypothesis accepted or rejected?
ACCEPTED!
Why?
There were more burps with Coke than with water based on the data and the results of the graph.

22. 6. Check for sources of error
Sources of error: things that may effect the results of the experiment
*Error can make the results of an experiment not valid!!!
Always look at the set-up of an experiment to check for error.

23. Possible sources of error:
Small sample size: fewer subjects may give inaccurate results
Unequal group size: you can’t compare the results of 2 groups if one group has 10 subjects and the other group has 50 subjects

24. Possible sources of error: (cont)
Not controlling (keeping the same) all variables except the one being tested
Length of the experiment (hours vs. days)
Amount of the variable (2 cokes vs. 1)
Type of material (coke vs. pepsi)
Other: light, temperature, age, health, gender, etc

25. Repeat the work:
When a hypothesis is supported by data from additional investigations, it is considered valid.
When a hypothesis is not supported, it means that we need to go back and ask new questions.

26. Checking for understanding
Two students decide to test the effects of Miracle-Gro fertilizer on plant growth.
They buy a rose plant and a daisy plant.
The roses are given Miracle-Gro and 1 cup of water/day and the daisies are given ½ cup of water/day.
The roses are kept in the sun and the daisies are kept in the shade.
The growth of the roses is measured daily and the daisies are measured each week.
What are some sources of error in this experiment?