Thanks everyone for your input. I think that, although I hadn't thought of it in those terms exactly, the idea of offering an extrinsic reward in order to bridge a skill gap and help DD5 arrive at intrinsic motivation is what I was getting at when I thought about offering pocket money for doing extra work on things she isn't particularly interested in (over and above what she is already expected to do). Thanks Dude and aeh for putting words to it. Portia, the coupon idea was a great solution! What an ingenious child!
