Stacking blocks turn simple stacking into an amusing, sensory experience. Handy grooves on the exterior keep the blocks aligned at various angles for creative tower designs. Crystal colors can be overlapped to let students explore color mixing concepts. Transparent construction can be used on a light table (sold separately) to create towers that glow. Teaching guide provides entertaining ways to enhance your activities with unique ideas. Stacking blocks are designed for children ages 3 and up.