One of the activities that is very common for teaching diversity or microbial diversity is the candy activity. In this activity, a sample community of candy is explored and used (and later, eaten) to make measures of diversity in a simple (and delicious) form. I elected to use jellybeans, since the known diversity would help us do this quickly. In this case, our richness is 49 (if your species definition includes flavor).
Kristen DeAngelis 