Estimating volume
Estimate volume of cuboids using 1 cm³ blocks; estimate capacity of containers using water
What a learner can do afterwards
- Build a cuboid from 1 cm³ blocks and state its volume
- Estimate how many cm³ blocks would fill a given box
- Estimate the capacity of a jug by comparing to known litre measures
The lesson
You already know how to find area: you count the squares that cover a flat shape. Volume works the same way, but in three dimensions. To find the volume of a solid shape, you fill it with tiny cubes. Each cube measures 1 centimeter on every side, so we call it 1 cm³. Count the cubes, and that count is the volume.
Zara builds a cuboid two cubes tall. Each layer looks just like the picture above: 8 cubes. She adds the two layers together: 8 + 8 = 16. Her cuboid's volume is 16 cm³.
You will not always be able to build a shape from real cubes. Look at a box and picture how many 1 cm³ cubes could fit along its length, width, and height. A pencil box might hold about 60 of these tiny cubes. That guess is your estimate of its volume.
Estimating capacity works the same way, but with litres instead of cubes. Look at a jug and picture how many 1-litre bottles of water it would take to fill it. If it looks like about one and a half bottles, estimate 1.5 litres, then pour water in to check.
Volume counts how many 1 cm³ cubes fill a shape, and capacity estimates how many litres a container holds, both checked by building or pouring.
Watch it
Where it sits
Learn first
This opens up
Where this leads
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.