Yes and no, I teach an aquatic biology course, and every Friday in the class is aquarium day. Students are allowed to choose an aquarium at the beginning of the term and they and their partners are required to maintain the aquarium (clean, do water changes, test chemistry, feed, etc.) At the end of each quarter, they receive a tank grade. Part of which is determined by me (based on how well they as a group performed their responsibility overall) and part is determined by their peers in the group (based on how well they as an individual helped to perform the task). At semester, if they choose, they are allowed to switch tanks. Some tanks I reserve for me, and generally don't allow students to be responsible for them, such as The Bog, and my 30 paludarium. Last year I had two groups of students who wanted to take on the task of building a paludarium rather than maintaining a tank, so they built two "bog" tanks in 40B turtle tanks for a couple other teachers.