I teach 3-5 year olds. Of our kids who are most likely to understand concepts such as exchanging money for one thing and using it to get something else, of the very sharpest of those, maybe those who are 4-4 1/2 -- the very very sharpest of those -- can understand the functional concept of fund-raising, or a lemonade stand. Even the brightest of the younger ones still think of selling as a sharing thing; they set up "pet stores" but after you buy the pets, you have to bring them back. The level of symbolic thought required to understand fund-raising or throwing money at a disease to find a cure is way way way beyond many four year olds, and I can't imagine more than one in a few million two year olds -- toddlers -- reaching that level of understanding. I'll bet Alex's mommy helped her think of it.