Unfortunately I can't remember which book this came from, it might have been "Raising Your Spirited Child" (terrible name, great book), but one of the most useful things I have ever read in a parenting book was to think of your child as a growing pyramid of blocks. Every 6 months or so they get another block and in order to have a well designed pyramid they can't just plonk that block on the top of the current pyramid, they have to knock it down and start again with all of the blocks. When they are going through a stage of "up-skilling" and re-integration expect outbursts. I felt like it really explained my kids' tendency to track along beautifully for a number of months and then fall apart for a while and then get back on track.
