Like most--probably all--parents, we have a mobile hanging over our little girl's crib. In keeping with the rest of the decor, it's a Pooh Bear themed mobile, with Pooh, Tigger, Pigglet, and Eeyore swirling around, looking down at usually-smiling L.
But that's very passive--lying there, watching Pooh and friends turn circles over your head.
Taking an idea from Baby Minds by Susan Goodwyn by Linda Acredolo (Amazon), we made it a more engaging--and thus, more educational--activity. All it took was the addition of a long piece of fabric loosely tied to L's left leg, with the other end end attached to the mobile. And voila!
It didn't take long for L to figure it out:
motion of leg = mobile mobile = very happy little girl
And with increased happiness came increased motion, until everything was a blur.
Now that she's got it, we'll change it, attaching it perhaps to her right arm--it will get her used to "real" life...