A study was created to test the effects of fear in children. The hypothesis of the experimenters was that if babies were exposed to fuzzy bunnies and at the same time a loud cymbal was struck close behind them then that child would be afraid of all fuzzy things. Another group of children would be exposed to bunnies without any loud nosies. The study was carried out as planned. As a result, hundreds of young children developed fear of cute, furry rabbits. What would be the dependent variable and what would be the independent variable?

I will start with the independent variable. The independent variable in an experiment is the variable the experimenter has control over. For example, if you are testing the effect of amounts of water on plant growth, the independent variable is the amount of water since that is was the experimenter is controlling. In the experiment you are referring to, the independent variable is the presence of the loud cymbal noises, since this is what the experimenter is controlling. Another way to think about the independent variable is to think about what is different between the experimental and control group. In this experiment, the only thing that was different was the presence of the loud noises, making that the independent variable.
The dependent variable in an experiment is the variable that is being measured and cannot be controlled. In the plant example, the amount of plant growth is being measured and cannot be controlled by the experimenter. In the experiment above, the dependent variable is how afraid the children are of fuzzy things because this is being measured and cannot be controlled by the experimenter. Another way to think about the dependent variable is to remember that the dependent variable 'depends on' the independent variable. For example, the amount of plant growth depends on the amount of water, and how afraid the children are depends on the presence of loud noises.