Swahili
Leo put some letter magnets on the board and told me he had written mummy.
I told him it also looked like a Swahili word, or a South African family name. Funnily I was right, it's both. Anyway, interesting that he correctly picked the m and the u and placed them approximately where they belong, and in general put the letters in the right position, not upside down or the like, though a zero has less options, and the m is actually an upside-down W.
In other news, for those who haven't heard it yet, he made a pun: on the changing table, he dropped himself, didn't move, grinned and said "Look! I fell asleep!"