Dependent vs Independent Variables 7 th grade science

Dependent vs. Independent Variables 7 th grade science

Two Parts to an Experiment 1. Control Group • Receives no special treatment • Used as a comparison to the Experimental Group 2. Experimental Group • Setup exactly as the control group, but with one difference. • Independent variable – one factor that is different from the control group. How does music effect sleep?

Two Parts to an Experiment 1. Control Group • Receives no special treatment • Used as a comparison to the Experimental Group Results: slept continuously for 6 hrs. 2. Experimental Group • Setup exactly as the control group, but with one difference. • Independent variable – one factor that is different from the control group. Dependent Variable Results: slept continuously for 8 hrs.

Is this a good experiment? 1. Control Group • Receives no special treatment • Used as a comparison to the Experimental Group Results: slept continuously for 6 hrs. 2. Experimental Group • Setup exactly as the control group, but with one difference. • Independent variable – one factor that is different from the control group. Results are invalid. Too many independent variables Results: slept continuously for 8 hrs.

The United States military wants to see if soldiers with only 4 hours of sleep can operate at the same level as those who normally get 7 hours of sleep. One hundred soldiers are allowed to only sleep for 4 hours a night and another hundred are allowed to sleep for 7 hours a night. During the day, the soldiers are tested for marksmanship on the firing range. 1. Name the Control Group: Soldiers with 7 hours of sleep. ___________________. 2. Name the Experimental Group: Soldiers with 4 hours of sleep. ___________________. 3. Name the Independent Variable: Amount of sleep given. ___________________. 4. Name the Dependent Variable: Score on the firing range. ___________________.

Farmer Bob wants to test a new fertilizer to help his crops grow better. He sections off two large areas of his field. In section A, he waters his crops as usual and uses his normal fertilizer. However, in section B he waters his crops as usual and then adds the experimental fertilizer. After 1 growing season, he records the growth of the crops. 1. Name the Control Group: Section A 2. Name the Experimental Group: Section B 3. Name the Independent Variable: Type of fertilizer used 4. Name the Dependent Variable: Growth of the crops

Constant A factor that does NOT vary in an experiment What should stay the same during this experiment?