A well-explained introduction to the concepts of area, perimeter, length, and width. Each Friday, Ms. Merkle has her students share objects as part of a mathematical show-and-tell. Zachary has a tendency to forget and must use his ingenuity to meet the assignment's requirements. One week, he uses a piece of paper to create a Moebius Strip, which serves as something to measure. The following Friday, he uses a scrap of paper to make an expanding frame for his lesson on perimeters. For his third assignment, he uses a flashlight to show the area of a rectangle. The text has realistic dialogue, and Zachary's ability to explain his projects to his classmates ensures that readers also have a very good chance of understanding the lessons. The plot also includes a rivalry between Zachary and another boy to give the most interesting presentation each week. This rivalry is well developed, and readers will recognize the classroom dynamics in action as the story builds. The resolution is believable and positive. Hohn's illustrations bring the story to life with plenty of detail. Sharp-eyed readers will notice that the blackboard lists the Friday assignments, further reinforcing the terms and concepts. At the end of the book, each of Zachary's three transformations is explained in well-detailed steps so children can try them on their own. Youngsters will find Zachary's quick thinking and solid explanations both entertaining and educational.