4 - 11 years. Children will be fascinated by these real specimen sets and teachers will love they are indestructible. These sets provide children the opportunity to learn about organism groups, life cycles, and parts of plants and animals. The complete specimen set includes twenty safe, lightweight, unbreakable acrylic specimens, and the smaller sets include four specimens each. Measures from 1.625" x 2.875" x 1" to 3" x 3" x 1".