What's the best way to explain autism (and other non visible special needs) to little ones?
The other day my 5 yr old was on a piece of playground equipment for one child and a much bigger boy came and sat on it next to her and gently started to force her off. I said to him 'DD was here first. Can you let her finish her turn' and then his mother arrived to explain he was autistic (in a really harassed way, she was simultaneously having trouble with her dog). So I asked DD to move because 'he doesn't understand about sharing'. At first she didn't move and asked 'Why?' because in her world up until know it's only younger children who don't understand about sharing.
So I had to explain within earshot of the boy and his mother and I said 'There's something not quite right in his brain so he doesn't understand about sharing'
Is this acceptable do you think? Any better way to explain it?