Making Soda with Long Term Care Residents

I work in a long term care facility for people with mental illness and thought it would be fun to brew with them. Obviously we can't brew beer so soda is the next viable option. Of course we can brew regular soda, but I was thinking it would be a better choice to brew diet soda since many of them are diabetic and overweight.

Has anyone brewed diet soda before? Can I combine real sugar and something like splenda so the yeast have something to eat but can't eat too much?

I don't drink diet soda, but you can certainly do that. You can make up the soda with artificial sweetener and then use real sugar to prime.