Control Groups vs. Experimental Groups

Mr. MahLiving Environment

10/22/09

Warm-Up Quiz

• Experiment: Does the amount of sleep affect a student’s grades?– Identify the INDEPENDENT VARIABLE,

DEPENDENT VARIABLE, and CONSTANT• IV: Amount of sleep• DV: Student’s Grade• Constant: Student, subject, test, etc.

Control Groups vs. Experimental Groups

Mr. MahLiving Environment

10/22/09

Experiment

• All experiments must have 3 things: independent variable, dependent variable, and control.

• When we conduct an experiment, we need something to compare our results to.– That is why the Control Group is important

Control Group:

• . Group in an experiment a scientist purposely keeps the same because the outcome is known

• Used to compare to the experimental group.– Scientists need to compare their results to see

what changed

Control Group?

• What is the control group in the following experiment?• Homer wants to see if eating donuts

before work makes him sleepy–Control Group: No donuts before work

• Experiment: Qadr thinks that dropping acid on your eyes will make you blind.– Control Group: No acid in your eye

• Experiment: Brandon wants to measure if going to the bathroom every block hurts his grades.– Control Group: Not going to the bathroom during

class• Experiment: Diashawn wonders if eating chips

every morning is healthy– Control Group: Not eating chips every morning

Experimental Group:

• Group in an experiment that is being changed in ONE way.

• The thing changed is called the independent variable.

• By changing the independent variable, scientists are looking to see if anything in the experimental group will be different from the control group.

• The difference scientists are looking for is caused the dependent variable.

Identify the Experimental Group• Experiment: Drinking more water makes you

go to the bathroom more.–Drinking lots of water

• Experiment: Eating school lunch increases your chances of getting sick.– Eating the school lunch

• Experiment: Paying Mr. Mah everyday will make you a better student–Paying Mr. Mah everyday

Practice• Terrece wants to see if eating candy in class

makes students more hyper in class– What are the IV, DV, constants?– Identify the Control Group and the Experimental

Group– IV: Eating candy– DV: How hyper students are in class– Constants: Amount of candy eaten, type of candy– Control Group: Students when they don’t eat candy– Experimental Group: Students when they eat candy