1. BELL WORK!
Sarah designed an experiment to find out which mouthwash was most effective against some bacteria. She cut out four different circles from a paper towel and soaked each circle in a different mouthwash. She put the circles on a nutrient agar-coated Petri dish that was covered with bacteria commonly found in the mouth. She then incubated the plate for 24 hours. The picture shows the results of this test. Put a star on pg. 16 in your composition notebook so I know you read this whole passage.
Which of the following should Sarah do to improve her experiment?
Use the same size paper circles for all mouthwashes.
Use the same type of mouthwash on each paper circle.
Use different kinds of bacteria.
Use a smaller Petri dish.

2. From Scientific Question to Hypothesis…
You will need a partner today and a sheet of notebook paper.
There are 15 questions on the wall.
Walk around and read them.
Choose five of them to respond to.
Write an If-Then hypothesis for the five questions you choose to respond to.
Sit down when you have finished.

3. Do you know the parts of an experiment?
Tuesday, August 23rd

4. Today’s Goals:
Differentiate between the experimental group and the control group in an experiment.
Identify the independent and dependent variables in an experiment.
List constants in an experiment.
Determine if bias or experimental error is present.

5. Parts of an Experiment:
Experimental
Group
The group that is receiving the independent variable; the “testing” group
Part of the experiment that does not get exposed to the independent variable; used for comparison
Control
Group
Example:
In an experiment in which blood pressure medication is tested, one group is given the blood pressure medication while the control group is given a placebo pill.

6. Parts of an Experiment:
Independent
Variable
This is what you physically change or test in an experiment
This is what changes because of the independent variable; this is usually what you are measuring in the experiment
Dependent
Variable
Example:
Sally gave Jim gum to see if he could blow a big bubble.
What did Sally physically do or test?
What happened when she gave Jim gum?
What was she measuring?

7. Parts of an Experiment:
Keep everything CONSTANT.
Test it over and over.
Get a big sample size.
Keep the Experiment Error Free
If I wash my hair with Suave shampoo, then it will curl easier.
Independent = Suave shampoo
Dependent = Ease of curling
Example:

8. Let’s Practice!
If I eat spinach every night, then I will get bigger muscles. Independent Variable: Spinach Dependent Variable: Muscles

9. Let’s Practice!
Hannah wanted to test if sugar affected how high bread would rise. Independent Variable: Amount of Sugar Dependent Variable: Height of Bread

10. Let’s Practice!
If I drink Mountain Dew every morning, then I won’t get a headache. Independent Variable: Mountain Dew Dependent Variable: Headache

11. Let’s Practice!
Does lunch detention affect behavior? Independent Variable: Lunch Detention Dependent Variable: Behavior

12. Let’s Practice!
Does lunch detention affect behavior? Independent Variable: Lunch Detention Dependent Variable: Behavior

13. Does gender affect aim? What was the independent variable?
Gender (boys vs. girls)
What was the dependent variable?
Aim
What were the constants?
Same distance
Same size target
Same object thrown