Ruth Spiro continues her mellow campaign to take toddlers beyond entry-level concepts (shapes, colors et al.) in her Baby Loves board book series. In Baby Loves Quantum Physics!, a toddler wonders if her cat, who is hiding in a box, is awake or asleep; according to quantum physics, "Until Baby looks in the box, Cat is both asleep and awake." In Baby Loves Thermodynamics!, a toddler's enthusiasm for body-warming daylight ("Good morning, Sun!") and apples from trees ("Baby eats the apple. YUM!") sets up a science lesson ("SUNLIGHT + AIR + WATER = FOOD FOR THE TREE"). Irene Chan's flat, chunky art is so uncomplicatedly jubilant that it's not readily obvious that there's a serious attempt to teach science afoot. --Nell Beram, freelance writer and YA author