You don't have too many sugars available to you: maltose and glucose from the LHBS, sucrose from the grocery store which might also have fructose (in the form of high fructose corn syrup), and perhaps invert sugar (Lyles Syrup) so it will be hard to illustrate that, for example, lager and ale yeasts ferment rafinose and mellibiose differently.
For the chemical process of fermentation (which is really quite involved) look up glycolysis in any biochem text or try the Wikipedia article.
With bakers yeast and table sugar I'm not sure you could do much except note how the reaction starts slowly, picks up speed and drops off, show how colder temperatures slow it down, demonstrate (by using grape juice for example) that the sweetness drops and other flavors emerge, distill off some of the alcohol (you can buy little stills from novelty catalogs). Bakers yeast will doubtless rip through glucose faster than an equivalent amount of sucrose as glucose enters EMP (the glycolytic pathway) directly where as the yeast have to synthesize a transportase to get sucrose into the cell, invert it and then send the fructose down a separate (partially) pathway.
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Science Experiment with yeast
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