Too bad you weren't able to successfully conduct the experiment.
A similar experiment was done on corn snakes in in a "real" scientific experiment. If your son is interested in reading about it, here is a link to an article about it:
http://www.rochester.edu/news/show.php?id=1514
For your son's future scientific endeavors, you might want to look closely into the requirements at his school. Most school sponsored science projects (at least in my experience) require special permission to work with live animals, so I'm a little surprised that does not seem to be the case here. It is usually just an extra form, with the idea to be sure that there is no cruelty going on. In my experience, it is WELL worth the extra work to get the kid working on something that REALLY interests them, but some teachers will discourage it.