Dd#3 has been knitting coaster size squares (garter st) for a several months on and off. She wasn't interested in learning how to purl.
Then I ordered Kids Learn to Knit by Lucinda Guy.
She found a cute little owl project in that book that she wanted to make. It required purling which she picked up in a flash. 2 stockinette squares later and some felt shapes cut and we've got Flapping Fred.
She now also knows how to cast on using the reverse loop method. She'll sometimes just grab yarn and needles and cast on over and over.
Polly Pocket also received a rug designed and knit by dd#3.
Happy Herbie is next in her queue.