I used to be a ski instructor at Keystone, and they have a large and very good ski school for children aged four and up. Copper Mountain's program is also excellent. The price of ski school includes equipment (at least at Keystone), and kids grow out of it so quickly I don't recommend buying any at all until they are older (middle school or later) and much more serious about it. Good equipment is also expensive, so unless you/they go really often it is not worthy buying. Renting is a graet option, or you could purchase used equipment. When they are old enough, and good enough skiers to warrant buying any equipment, the most important thing is boots...go somewhere that has expert boot fitters (I have been impressed by Christy Sports in the past). How the ski boot fits will greatly impact comfort, warmth, even (and mostly!) technique. Skiing is a wonderful, life-long sport. You should ALL take it up!