Tiger Tales has published a series of board books that have a sliding panel. There is a question on each spread and the answer is revealed when the sliding panel is pulled up. For this book, the questions all relate to eggs. Clues are often given if you look at the panel or the picture. For example, a hen is looking at her egg and asking "What's in the egg?" When the tab is pulled it reveals a baby chick. One might quibble about some of the entries such as a shark producing eggs and its young hatching since many sharks give birth to live baby sharks. Young kids will learn something and have fun moving the sturdy slides up and down. Whose Hat Is That? Who Lives Here? and What's in the Box? 2004, Tiger Tales, Ages 2 to 4.