I put an absorbant towel like the ones used to clean windshield,
blue and thicker,  in oven when doing hand processing of kidney biopsies.
The mess was contained nicely.  Embedding is another story, a used
embedding center might be a good investment, or at least a paraffin
dispenser, making do with a slide warmer (not overly hot, I cooked
tissues this way once!) at 58- 60C to keep the tissues warm.  Cassettes will
certainly cut down on so many little vials, easier to handle, and the ones
with disposable lids are microtome ready once wax solidifies after embedding.  
 
There are colored cassettes that could help your students identify their
specimens, or groups of students.  Interesting logistics here!

Good luck,
Gayle Callis