I tried Heddy with my children. It worked great at first. It's really easy to get started with. Every level, the language changes slightly to introduce more concepts. That worked great for my younger son, but it confused his brother. Code that was correct in one level, suddenly gives errors in the next. In the end, we stopped using Hedy. I now teach them Python instead. It's harder at first, but at leastthe things they learn, won't change.