You can use a glossary as a collaborative activity. In this case, it is similar to a wiki, but you can impose stricter guidelines and add very specific instructions.
For example, in the case of a definition of EcoTourism, students can contribute their own experiences and also add links to blog posts that illustrate their experiences. The student can first add the official definition and then an example in a very succinct manner. Continuing with EcoTourism:
Tip
EcoTourism- Ecologically sustainable approach to tourism that targets places that are unique because of their ecology. The touristic experience focuses on active participation and has a goal of building cultural understanding, appreciation, and conservation.
Here is an example of protecting endangered sea turtle hatchlings in the Pacific coast town, Lo de Marcos, in Nayarit, Mexico. Here is a blog post I wrote about the experience (http://fringejournal.blogspot.in/2015/12/tortuga-twilight.html ):
You...