The other day Jamie was napping and Maggie wanted to play boffers with me. So we started swinging the swords at each other. Well, I swung--gently--at her. She waved hers around randomly. So I spent some time explaining parries and slowly moving my sword in to tap her stomach so she'd have a chance to block it. Made a little bit of progress.
Then she went down for her nap and Jamie got up. I gave him a turn with the boffers. No need to teach him about parries, he was instinctively batting at my sword whenever it came near him. Not that he was good at it--once he pulled a belly shot into his cheek. But he had the right attitude.