Manipulated Variable (Independent variable)  the variable that is deliberately changed by the scientist. “What is the scientist changing in this experiment?”

Responding Variable (Dependent variable) the variable that changes as a result of the change in the manipulated variable. “What is the scientist looking for or trying to measure?” Or “What is responding to the changes?”

controlled variables  all the variables that are kept the same so that any change in the responding variable can be attributed to the change in the manipulated variable “What does the scientist have to do in order for this to be a fair test?”

Example #1

Does heating a cup of water allow it to dissolve more sugar?

Manipulative/Independent variable?

Manipulative/Independent variable Temperature of the water measured in degrees Celcius

Dependent Variables?

Responding/Dependent Variables Amount of sugar that dissolves completely measured in grams

Controlled Stirring Type of sugar "More stirring might also increase the amount of sugar that dissolves and different sugars might dissolve in different amounts, so to insure a fair test I want to keep these variables the same for each cup of water."

Example #2 Does fertilizer make a plant grow bigger?

Manipulative/Independent variable Amount of fertilizer measured in grams

Responding/Dependent Variables Growth of the plant measured by its height Growth of the plant measured by the number of leaves

Controlled Same type of fertilizer Same size pot for each plant Same type of plant in each pot Same type and amount of soil in each pot Same amount of water and light Make measurements of growth for each plant at the same time