The Very Hungry Caterpillar
by Eric Carle · 1969
Counting, days of the week and a life cycle are folded into one short, repeatable story, and the die-cut pages invite small hands to poke and turn.
Consider: The science is simplified (caterpillars build a chrysalis, not a cocoon, before becoming butterflies), so older preschoolers curious about insects may want a nonfiction follow-up.