Another approach I often use is playing games with...

# random

[orangy]

Another approach I often use is playing games with math and world around. E.g. we have 3-digit car plates (plus some letters, but we ignore them). We assume plate to be “magic” if there is a digit equals to sum of two other digits. Kids run around finding “magic” plates, and learn how to sum, but then they discover some more properties of numbers, like how to discard obviously non-matching numbers quickly.