I think you're right with the sharing clep. However, we can start really developing it earlier. Cooperative play begins between 2 and 3...once that begins, your toe is well in the door. Before that, in the Parallel Play stage, it's pretty much hopeless. They don't get it and don't care to get it.

Shadowing is a great tool, and my professors touted it regularly. However, it can be pretty tough to keep on top of depending on what's going on with the other kidlets in our care.

I used 123 magic with my sons when they were little. I gave up for the very reason you mentioned...little stinkers. They're both in high school now, but I remember them grinning at me as they recited the next number. FRUSTRATING....but somehow still cute! They always waited till the last number. It was only the time out or loss of a privilege that got their attention and brought an end to the behaviour....for that day.