My younger daughter is nine. After watching me sit with a laptop all term preparing material using Scheme, she wanted to know something about it. She is self-taught on the application side of computing (browsers, paint programs, word processing) but knows nothing of computation itself. So I opened up a DrScheme Interactions window. “You add like this,” I said, typing in (+ 3 4). No problem. “Try some other operations, some bigger numbers.” It looks like a calculator without a ten-digit limit.
I wrote out some arithmetic expressions for her to convert to Scheme. She had difficulty with them, but not with Scheme: I had forgotten how much algebraic notation is taught later. She didn’t understand concatenation for multiplication, / for division, or putting two expressions one above the other with a horizontal line in between. Once I explained those, she converted them into Scheme expressions very quickly.