The Volume Relationships Set includes six commonly found models, including cubes, cuboids, cylinders, spheres, quadrangular pyramids, and cones. These important models will help children visualize different three-dimensional shapes and volumes. All models are designed to have a width or diameter of 10 cm, so that children can begin to intuitively grasp the differences between them. All models have an open side so that they can be filled with liquid or sand to demonstrate how volume affects content.