You’ve got to introduce the science (or whatever new concept you’re dealing with) before you need it.
This just occurred to me as I was out strolling with F. (Yes, friends, exercising more than just our fingers is good for our writing.) I know I’m not the first writer of nonfiction picture books to figure this out, but I thought someone else out there might benefit from me stating what must seem obvious to others.
When the story needs the science, it needs an understanding of it, not an explanation. Take time to explain right then, and you might well lose the reader. Casually slip in the concept a bit earlier, and the understanding of it is more likely to be there when the story demands it.
And that’s what I learned while pushing a stroller three miles through my neighborhood. That, and the fact that Day-Glo colors are mighty popular for garage-sale signs…