Idea 21of 22Builds onSmall unit to big unit: divide
Compare in the same unit
How do you compare two amounts in different units?
Today you'll discover
- why the bigger number can be the smaller amount
- how to put both in one unit
- how to check with a drawing
Think firstRibbon A: 1.2 m. Ribbon B: 98 cm.
Which ribbon is longer?
Decide first, then press Next. Look at the units, not just the numbers.
Two rows: ribbon A, 1.2 m, and ribbon B, 98 cm. Then each is written in centimetres: 120 cm and 98 cm. Then two strips drawn to the same scale, the first one longer, and it is ringed: 120 cm > 98 cm, so ribbon A is longer. The last step compares a 2 L bottle with a 1800 mL jug.
See the whole ideathe big idea and the key word, in one place
The big idea
Write both amounts in the same unit before you compare the numbers.
Easy to get wrongA bigger number is not always more. 98 cm is shorter than 1.2 m.
Putting heights in order1.45 m, 139 cm and 1.4 m: in centimetres they are 145, 139 and 140, so 139 cm is the shortest.
Key word
- same unit
- both amounts written in one unit, so their numbers can be compared
Ready to use it?
- Compare two measurements in different units.
- Order measurements from least to greatest.