intooba construction kits are designed for hands-on collaborative group work by students in K-6. Our large kits are supported by a common core linked K-6 Math curriculum, and two Engineering student manuals (K-3) and (4-6). Our Engineering manuals have over 24 challenging building exercises, each with several levels of complexity. Large kits contain 372 pieces and are good for 12-15 students working in groups of 3 or 4.www.intooba.com