In your experiment, you tested this hypothesis:

Hypothesis: If molecules are small enough, then they will diffuse across a semipermeable

membrane because they can pass through its tiny openings.

The independent variable in this experiment was

and the dependent variablewas

The dependent variable in this case is the valuable whose value is dependent on the other variables. In this context, the dependent variable is the rate of diffusion of the molecules ... how fast or how slow which is depends on the size of the molecules.

The independent variable is the usually has a direct effect on the dependent variable which in this case is the size of the molecules ... how small or big ... will affect their rates of diffusion.