After two weeks of madly modeling head nodding, saying 'DS2, do you want ___? YES!' and doing the Makaton sign (God knows what I must look like in public - like some sort of deranged nodding dog I should think) he finally did it all by himself. We were at an adventure park and I noticed he was looking at the carousel, so I said 'DS2, do you want roundabout?' and he said 'Yes'.