Experiments

I don't plan on teaching psychology, so I was going to refrain from blogging about it. However, we are working on a project where the students create their own simple studies, conduct the study, and then analyze and present their results. The goal is to teach about scientific method by creating experiments. Now that we are about half way through the work I'm seeing all sorts of flaws with the assignment as well as many ways to improve things. Any thoughts on ways to make experiment creation a worthwhile project (I'm especially looking at you science teachers!)?