Struggles in mobility-training

I remember pretty well an instance in which a visiting friend was building block towers for baby Rip to smash down, which he would do with great delight. The friend kept moving the block towers further and further away, in the hope of encouraging baby Rip to try to army crawl or otherwise exercise mobility. When the tower got so far that Rip couldn't reach with his hand, what happened instead is that Rip grabbed a piece of train track and used it to bludgeon the tower down, triumphantly. Fair enough. Problem-solving win, mobility-encouraging fail.

I was reminded of this by the way that Tammy knocked a toy she'd been playing with out of her reach. Ephiny encouragingly said, "Hey! That toy is just out of your reach! What are you going to do about it? Are you going to reach for it?" and Tammy instead practiced serene acceptance of the situation for a moment, contemplating the toy and its out-of-reachness without particular disgruntlement or attempt to reach. A minute later, Rip walked by and said, "Hey, baby, do you want this toy?" and handed it to her. Ha.

And that is the story of why Tammy doesn't crawl. She has people to do that for her.