3 years and up. This Color Crystal Block Set with Activity Cards can help children learn to fit shapes together and expand their understanding of spatial relationships, geometric vocabulary, and color recognition. This transparent acrylic block set features 17 different regular and irregular shapes in 5 translucent colors. These manipulatives will also spring to life when used with a light panel or in front of a sunlit window. The blocks create colorful streams of light and eccentric shadows. The included mirror provides an opportunity to observe reflection. Children can also explore color mixing. Made from extra thick acrylic plastic, these colorful shapes are designed to last for years. Use the 15 activity cards and a teacher's guide for extended learning ideas. Largest block measures 3.1"W.