Variables Ms. Underberger September 2, 2015

A variable is what you are trying to measure. There are 4 types of variables.

1. Independent Variable Causes changes in other variables The experimenter often chooses the independent variable

2. Dependent Variable Is changed by the independent variable The “effect” of the variables impacting it Experimenter cannot control the dependent variable

3. Control Variable Does not receive the independent variable What is considered “normal”

4. Constant Variables What is the same for all variables and parts of the experiment Usually relates to materials

Example with FRED Question: How can we put the lifejacket back on FRED without knocking him off of the cup and using only paperclips? Hypothesis: I predict if we open the paperclips and loop them under the cup, then we can lift the cup and get the lifesaver to stretch and put on FRED. Independent Variable: Bending of the paperclips Dependent Variable: Lifting up cup & getting lifesaver on FRED Control Variable: Keeping paperclips as are and not opening or bending them Constant Variable: set-up of experiment, materials, rules

Example: Fertilizer Question: How can I make my flowers grow taller? Hypothesis: If I put fertilizer in the soil, then the flowers with fertilizer will grow taller in 1 week than flowers without fertilizer Independent Variable: fertilizer Dependent Variable: how tall the flower grows Control Variable: plant without fertilizer Constant Variables: 1 week time frame, pot size, type of soil, type of flower, watering plant daily recording height daily