Three-dimensional shapes include cubes, rectangular prisms, cylinders, cones, and spheres. They have faces (flat surfaces), edges, and vertices. Sort 3D shapes by properties like whether they roll, stack, or have curved surfaces.
You already know how to recognize 3D shapes — a sphere, a cube, a cylinder. Now the focus shifts from naming shapes to thinking carefully about what makes each one different, and using those differences to sort shapes into groups. The key insight is that a shape's properties determine what it can do. This turns geometry into something you can test with your hands.
The three most useful sorting properties for 3D shapes are: rolling, stacking, and flat or curved surfaces. A sphere rolls easily in any direction because its entire surface is curved — there are no flat faces to stop it. A cylinder rolls in one direction (on its curved side) but stands upright on its flat circular ends. A cube and a rectangular prism have only flat faces, so they stack and slide but do not roll. A cone rolls in a circle around its point. Sorting shapes by these behaviors connects how a shape looks to what it does in the real world.
When you sort shapes, you are grouping them by a rule — a shared property. "Has at least one curved surface" puts spheres, cylinders, and cones together. "Can stack flat on top of another shape" collects cubes, rectangular prisms, and the flat ends of cylinders. Notice that some shapes fit into more than one group depending on the rule. A cylinder has both a curved surface and flat faces. A cone has one flat face and one curved surface. This is not a problem — it shows that shapes can be described in multiple ways.
Learning to sort 3D shapes by properties is practice for a deeper mathematical habit: organizing objects by shared attributes. The same thinking — "what rule puts these together?" — reappears in data, in algebra, and in science. For now, the payoff is that you can predict a shape's behavior before testing it. If a package is a rectangular prism, you know it will stack neatly. If a ball is a sphere, you know it will roll in any direction. Geometry becomes a tool for reasoning about the physical world.