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
1 · Read
You know how litres tell how much juice a jug holds. For a solid box we count cubes instead. 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.
More to read
Metric units of volume review (L and mL)
Volume tells you how much space is inside something, like a bowl, a box, or a bottle. When we measure liquids like water or juice, we use milliliters (mL) and liters (L).
A single raindrop holds about 1 milliliter of water. That is really small! A big bottle of water usually holds about 1 liter, which is the same as 1000 milliliters.
1 milliliter of water takes up the same space as 1 cubic centimeter (1 cm³). So if you built a tiny hollow cube out of 1 cm³ blocks and poured water into it, it would hold about 1 mL. That is how block volume and liquid capacity connect.
Next time you see a jug or a cup, try guessing how many liters or milliliters it could hold before you check.
Units of measurement: FAQ
Why bother estimating volume? In real life you cannot always measure things exactly, so a good guess is often what you need.
Say you are pouring water into a jug. If you know a carton holds 1 liter, you can look at the jug and guess whether it holds about half a liter, one liter, or maybe three liters, just by comparing sizes in your head.
The same trick works with blocks. If you know one small cube is 1 cubic centimeter, you can look at a bigger box and estimate how many of those cubes would fit inside, without counting every single one.
Estimating is a skill you use anytime you cook, pack a bag, or fill a water bottle. The more you practice comparing sizes, the better your guesses get.
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2 · Watch
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Where it sits
Learn first
Optional connections
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Nothing builds on it yet.
Where this leads
14 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.