Geometric Reasoning: Counting Cubes

Methods in this video

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1. 1

   Count one layer, then count the matching layers

   ▶ 0:32

   When to use it: A solid built from small cubes, or a box that holds them: how many cubes, which have the same volume, how many objects can be made, how many more are needed. A box folded from cut card counts too.

   • One layer is rows times columns. Multiply by the number of layers, or add the layers if they differ.
   • Count what you can't see: a cube on top always has a cube holding it up.
   • No cubes drawn? Find the sizes first. One face is one layer. A folded box loses the cut at both ends.