Engineers faced a problem when they needed a compact bridge that still allowed naval traffic. When faced with the same problem, students think critically as the answer literally materializes before them. As they assemble the high-quality wooden pieces in this kit, students explore simple machines like gears and crankshafts to understand the inner workings of a lift bridge. The result is a working replica of the many lift bridges constructed over the last 100 years. As one of the most common bridges used for freight railroads, students will come to understand important mechanical principles that are present in the real world. This kit is the perfect companion to an engineering unit, as it serves as a hands-on demonstration of the concepts discussed. Recommended for Elementary and up.