"Could you explain to the students what you are proposing?"
There are two main places I want to point students looking for project ideas. The first is to look at the list of potential student-project bugs, available here. This list (106 bugs at the time of writing) is constantly changing as people add new things, and students take others. While I'm on the topic, I have to thank a few people who work hard to keep this list fresh: Boris (bz), Benjamin (bsmedberg), and Mark (Standard8). These three are the names I see most often when I get notifications from bugzilla of new things being filed/flagged. These guys are among a group of a dozen who regularly take the time to triage bugs for new contributors and students. We need more like them (in many ways), and always need more project ideas for those times when 31 French students show up (it happens!).
The second main project area where we have a lot of students working right now is on something we're loosely calling Processing for the Web. The part of this project where we're currently focusing our energy is on implementing the rest of the processing.js, see the task list here, which includes adding the 3D support. As we go we are keeping track of performance issues, too, and hope to feed these back into the platform team so we can insure things get faster as we build more and more. This week, the ten students I have working on this have their first set of functions due, and we'll be adding a baker's dozen or more new function implementations to the library. Here's Andor's demo of mag() and Matt's demo of pushStyle() and popStyle(), for example.