Maria is preparing an experiment using three cups, one made of paper, one of plastic, and one of glass. She plans on pouring 50 ml of hot water into each of the three cups and recording the temperatures in 5 minute intervals. What is the independent variable in this investigation?
INdependent variables: volume of "hot" water. There is no indication of what hot means, or the intial temperature in each cup is the same.
I would disagree with bobpursley. The independent variable is the material of the cups. Assuming the initial temperature of water was the same in all three cases, the dependent variable is the temperature of the water.
The null hypothesis (Ho) is that the material of the container will have no effect on the temperature change of the water.
An independent variable is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.
A dependent variable is the response or measure of results.