Base Times Height

Find volume from the base's area and the height.

Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.

What children learn in Level 5

Why count cubes when a box's base already tells you the layer? The base's area, in square units, matches the cubes in one layer.
The height tells how many layers fit. A height of 2 units means 2 layers. So the volume is the area of the base times the height.
Here's a storage box. Its base has an area of 64 square units, and it's 8 units high. That's 8 layers of 64 cubes.
You don't need a rule to memorize. Just think: how many in a layer, and how many layers?

Georgia's K-12 Mathematics Standards:

5.GSR.8.4 — Discover and explain how the volume of a right rectangular prism can be found by multiplying the area of the base times the height to solve authentic, mathematical problems.