1. Designing Good Experiments Do Now: Please copy the following definitions into your notes: Dependent Variable: The variable in an experiment which is measured as a result. It’s value depends on the value of the independent variable (example: how long termites followed an ink trail) Independent Variable: The variable in an experiment whose values are selected by the experimenter. Finding the effect that changing this variable has is the purpose of an experiment (example: ink color) Control Group: The samples or trials in an experiment that DO NOT get any experimental treatment. It is what the other groups will be compared to. (example: termite behavior with no trail)

3. Know your Variables! Jeff wants to figure out the effect of using hand sanitizer on the number of bacteria on his hands. He will measure the number of bacteria by putting his hand on a petri dish and then counting how many bacteria have grown there 3 days later. He does three trials of the experiment: one without using any sanitizer, one with “brand x” sanitizer, and one with “brand y.” What are the independent and dependent variables of the experiment? What is the control group?

4. Milgrim’s Weird (& Disturbing) Experiment As we watch the video about the famous Milgrim psychology experiment, ask yourself: –What is the independent variable? –What is the dependent variable? –What is the control group? / Is there a control group?

5. Refresher Independent Variable: selected by experimenter trying to figure out what effect it has. Dependent Variable: measures the effect of the independent variable. Control Group: gets no experimental treatment. Independent variable = “0”