My daughter takes adult liquid vitamins, but just half the recommended dose. I slip it in her morning drink, and she loves it. The one we use is called Peter Gillham's Natural Vitality, Organic Life Vitamins, Organic Raspberry-Cranberry , and we order from iherb.com. Here is the link, http://www.iherb.com/
If you have never ordered from there, you can use this coupon code NIF211, I think you get $5 off or something. I like this liquid vitamin because it is food based, and more bioavailable than some others. My daughter likes the flavor, so we stick with it, although I think any liquid you can hide in juice or whatever would do the trick. Hope that helps, good luck!