I've been using LEGO to help my kids learn math. Here my daughter is working on multiplication. She doesn't know it, though. She just knows that we're putting together stacks of two bricks, and counting the size of the resulting stack.
Then I taught her that we could write out the multiplication table we just built in bricks, where the 'x' stood for 'groups of', so 1 group of 2 is 2, 2 groups of 2 is 4, etc.