"Let's Find Out What's Light and Heavy" by Martha and Carles Shapp is a vintage children's book from 1975 that explores the concepts of light and heavy through engaging storytelling and illustrations. As a part of the "Let's Find Out" series, this hardcover book is written in English and is suitable for young readers ages 4-12. With ex-library markings, this picture book features the illustrations by Robbie Stillerman and is a valuable addition to any collection focusing on children's literature from the 1970s.