The very best environments will have other kids who are engaged. It is induction into a culture, with its own language, ways of thinking and values. If you can't find that directly, you have to do your best to create a mini version as a family.
You can turn almost anything into a little maths games, card or dice games provide an opportunity for probability puzzles, the environment provides things to estimate and count, you can challenge them on car trips with rates and distances, etc etc etc. How many sides does a circle have?