Question

Suppose you want to test the hypothesis that plants grow taller when they receive more sunlight. Identify and independent variable and a dependent variable for this investigation.

Answer 1

The result that should be established is in the form
y = f(x) 
where x, the amount of sunlight is the controlled (independent) variable,
y =  height (growth) that corresponds to the amount of sunlight. Therefore y depends on x.

Clearly,
x, the amount of sunlight is the independent variable. It can be controlled.
y, the measured amount of growth is the dependent variable.

Answer:
The independent variable is the amount of sunlight.
The dependent variable is the growth.