[HuShifang]

Second the Beast Academy recommendation. I'd add, it's the younger version of Art of Problem Solving. The interactive games are extremely well designed from a pedagogical standpoint, the videos are fun and clear, the visuals are appealing, etc. (And I will say, there's a TTS button on the screen so that a kid who can't read can still hear the instructions, which are usually pretty intuitive anyway, especially after the video walkthrough. And the accompanying comics have proven more supplemental than essential for us.)