This is tricky,I have thinking about the same thing. Maybe students could identify the "substrates" of your campus (ours would be soil, grass, and concrete) and then some organisms to look for (insects?) and use quadrat point sampling or something similar. The students could use a campus map to create their sampling design.
Maybe the greater purpose is to look at native vs . invasive species on your campus, or to find the "need" related into what species should be introduced. I am just brainstorming :) On our campus we would find a large degree of soil as substrate, and student scientist may want to propose alternative substrates to campus officials. We could share our results with administration.

I was trying to figure the same thing out for my students to make it more real life related. After reading the suggestion offered I was thinking about the same idea but having them identify trash or gum counts and then offer suggestions to improve the numbers if they are high (which I think they will). Or do a comparison between the 'trash' type numbers and actual living organisms. We also have a lot of newly planted plants that keep getting run down by the students and maybe this could lead to a school announcement type program about keeping the plants alive.... Not sure but if anyone else has ideas, I'd love them too.