[gumby]

Read the text books, or when little the handouts, to see what they are being taught. When they are big enough for textbooks it will probably shock you, especially history and the like. Anyway, just play with stuff related to what they are learning, and play is the key word.

Most math education is syntactic transforms, not understanding. There are lots of skill-appropriate puzzles in books and online you can do together so your kid can see that math can be fun. Same applies to other subjects — learning about US history? Make a trip to some local historical thing and when kiddo is bored just run around or whatever.