David Macaulay is at it again with another phenomenal book. Join Sengi and Sloth on their adventure to escape the zoo with page after page of pop-ups, pull-outs, and interactive hands-on elements here, all of which playfully explain the physics of simple machines — and more complex ones, too. Developmentally, eight- and nine-year-olds benefit from manipulatives to help teach abstract concepts, and this book utilizes this approach to create an engaging and educational reading (and playing) experience.