Measuring more exactly and a part of a unit
Measure with your own unit, count the small parts of a centimetre and find the middle of a line.
📖 Start here: read the steps of the “Lesson” in order (1, 2, 3 …) and answer each question. Then continue with “Practice”.
- France: grade 3
- Iran: grade 2
Guide
Anyone can make their own unit, for example a paper strip. If your friend's strip is longer or shorter, you get a different number. That is why we use standard units such as the centimetre.
Each centimetre on a ruler is split into 10 equal parts. One small part is a millimetre: 1 part out of 10.
If something is 2 centimetres and 6 small parts long, it is 2 cm 6 mm. Altogether that is 26 millimetres.
To find the middle of a line, measure it and halve the length. Then go that far from the start of the line.
Drag the ruler with your finger, or tap it and use the arrow keys. The ruler's 0 must be at the start of the object.