My six year-old son is very extroverted, and prefers to play with someone. My three year-old daughter is strong-willed but introverted, and prefers to play on her own. When they play together, my son is very controlling trying to maintain my daughter's participation in his activity of choice, which inevitably leads to conflicts. We are working on teaching him more sociable ways to play, but the bottom line is that in the mean time, playing together is very stressful on my daughter, and playing apart is very difficult for my son.
We give him several chances to make it work in the same room, but after that we usually end up making him play in his room for a while. This gives respite to my daughter, but my son perceives it as a punishment. To a certain degree, that's okay, since he is the instigator and the one invading his sister's space. However, giving my daughter enough alone time makes my son's perceived punishment too harsh, but reducing the time apart to make the punishment reasonable doesn't give my daughter enough alone time.
So you can see our dilemma. What ideas do people have for isolating an extremely extroverted child without him perceiving it as a punishment? Put another way, how do you help an extremely extroverted child learn to enjoy playing on his own?