2. ASSIGNMENT LOG #1 8/25 8/29 Mission Possible -Cooperative project 100/ 15 8/31 9/2 Tools of the Trade 145 9/1 9/1 Cooperative -Tool ID 15 9/2 9/9 Interactive Reader -Pgs 20-27 - Sidebars, Highlight Answer in text & #1-5 on pg. 27 65 9/6 9/13 BioTechnology Virtual Lab 160

3. Independent and Dependent Variables Scientists use an experiment to search for cause and effect relationships in nature. In other words, they design an experiment so that changes to one item cause something else to change in a predictable way. These changing qualities are called variables . A variable is any factor, trait or condition that can exist in differing amounts or types . An experiment usually has three kinds of variables : independent, dependent and controlled.

4. The scientist focuses their observations on the dependent variable to see how it responds to the change made to the independent variable. The change of the dependent variable is caused by and depends on the value of the independent variable . Experiments also have controlled variables . Controlled variables are factors that a scientist wants to remain constant (the same), and they must observe them as carefully as the dependent variables. Controlled variables are used to compare the dependent variable’s changes in experiment’s relationship and keep the tests fair.