Suggestions for propagation experiments
Over on the propagation forum at http://forums.gardenweb.com/forums/propa/ there is a flurry of discussions about dipping cuttings in things other than propagation hormones like baking powder, powdered sugar and honey.
This offers a number of potential experiments for students or the tinker. I would suggest waiting until leaves fall and then take Poplar or willow cuttings. Set up controls in water, soil, soil & hormones. Then treat tests in the same manner as the three controls.