1 Key Question  What makes a good biology experiment?

2 Scientists ask questions about the world.

3 Why ask the questions?  People are curious.

4 Farside Cartoon: G. Larson “Notice all the computations, theoretical scribblings, and lab equipment, Norm…Yes, curiosity killed these cats.”

5 What Makes A Good Biology Experi- ment?

6 What Makes a Good Experiment ?  1.  2.  3.

7 What Makes a Good Experiment  1. Honesty  2.  3.

8 What Makes a Good Experiment  1. Honesty  2. Scientific Method  3.

9 What Makes a Good Experiment  1. Honesty  2. Scientific Method  3. Correct Equipment

10 WAIT! Scientific Method …..What is that???

11

12 Start Note sheet Start Note sheet

13 1. Ask a testable Question. Example: Does watching T.V. make you fail Biology class?

14 2. Form a Hypothesis.  Educated guess.  Never in a question form.  If/Then form  What is a good hypothesis for our Bio grade/TV example?

15 3. Design a Controlled Experiment: 3. Design a Controlled Experiment: An experiment where only one variable is being changed at one time. There is a control group. And there is an experimental group.

16 3a. Control Group The group that stays the same. The scientist keeps this group the same on purpose so we can compare the data with the experimental group. Ex. plain cheeseburger vs. Big Mac What is a good control group for the question biology grade and TV?

17 3b. Experimental Group The group with the change. Only one variable (condition) is changed at a time. What is our experimental group? Bio grade/TV?

18 3c. Independent Variable The variable the investigator is testing. The variable the investigator is comparing. Ex. plain cheeseburger vs. Big Mac Independent=I did it Or Independent = Investigator did it. What is our independent variable?

19 3d. Dependent Variable The variable that can be measured at end of the experiment. What is our dependent variable? What can we measure after one group watches tons of TV and one group watches no TV? What can we compare?

20 3e. Replication: Repeat the experiment many times.

21 The number of subjects in the control & experimental groups. 3f. Sample Size:

22 3g. SAFETY!!!  For the researcher  For the Environment (Inside or outside labs)  For the test subjects (like animals)

23 Early Experi- ments in Transpo rtation.

24 3h. Identify sources experimental error.  1. Bias: Preconceived ideas that influence experimenter.  2. Operator Error  3. Equipment Failure

25 3g. How can you prevent bias??  Placebos- ½ test subjects give control or fake variable  Blind Study- test subjects don’t know if they have placebo or real  Double blind- test subjects and scientists don’t know who has placebo or real

26 4. Collect Data. Think about how best to set up a data sheet.

27 5. Analyze data. Create a graph, chart, or map to organize collected data.

28 6. Form conclusions. What patterns do you see?

29 7. Repeat Experiment. Do not change any variables!

30 Wrap Up  What makes a good biology experiment?  Honesty  Scientific method  Correct equipment