We have used ShillerMath for 5 years now. My oldest began with Kit I and is now nearing the end of Kit II. I now have 4 other kids using ShillerMath, and a 2 year old eagerly awaiting the day that he is able to start doing math. It has been such a great value for us, has made teaching math so easy for me, and has given my kids such a great understanding of math concepts.