It's working pretty well lately to set the kids in front of a big bin of toys during playtime and just let them pick. Sara likes to pull one out, look at it for a minute, and toss it behind her.
She has also figured out how to get into the bin while she is supposed to be having tummy time. Hard to have tummy time when you roll over on your back and s-t-r-e-t-c-h...
As for Adam, he tips the basket over so all the toys fall in his lap.
Then he tries to pull himself up on said basket, until it tips over and he falls inside! "Might as well play while I'm here!"