We brought our kids downhill (alpine) skiing this past winter. Our 3yo did not have the leg strength to do it unless one of us held her upright. Our 5yo took to it like a fish to water, though. By the end of the season he was skiing intermediate trails with ease.
I just discovered your blog today (from the link on Teaching TinyTots) and I just love your ideas. I have a 22 month old and we are getting ready to start some homeschooling in a few weeks. I am definitely bookmarking your site and will be back for some more of your fabulous ideas. Great blog!!