How Much Space?
Measuring volume — even of a lumpy stone
What this lesson covers
Why it matters
A ruler can measure a brick. But how do you measure the SPACE inside a lumpy stone that no ruler fits? Hint: the stone can't swim.
Predict first
Drop a stone into a measuring cylinder of water. The water level…
The stone needs room, so it shoves aside exactly its own volume of water — read the rise, and you've measured the lump.
- rises by exactly the stone's volume — correct
- stays the same
- falls
What you do
Dunk the lumpy stone — the water level jumps, and the RISE (not the level!) is its volume. Then measure two mystery blocks and unmask their metals.
Check yourself
Volume is measured in…
Volume is 3-D space: cubic centimetres, cubic metres, litres (1 L = 1000 cm³).
To find the area of a leaf (an irregular shape), you would…
Irregular shapes defeat rulers — the graph-paper square-count is the Selina method.
Water rises from 30 mL to 42 mL when a marble drops in. The marble's volume is…
The RISE is the marble: 42 − 30 = 12 cm³.
- cm³ or litres — correct
- grams
- metres
- trace it on graph paper and count the squares — correct
- measure it with a ruler alone
- weigh it
- 12 cm³ — correct
- 42 cm³
- 72 cm³