I got these cups for my kids for Christmas. I am impressed with both of my children, because they read the little instruction book that comes with it, and learned how to speed stack the right way. There are a lot of steps to learn and a certain way to do it fast.
It is really cool to watch them. It's just a simple thing but watching them and listening to them explain how to do it is really fun and I am yet again amazed at how smart they are and good at understanding things easily.
