Explore · Mathematics · Mathematical Thinking

Numbers on a number line

Select and use appropriate tools and representations (number lines, hundred squares, rulers, part-whole models) to support problem-solving

ages 6 to 78 practice questionsvideo included

What a learner can do afterwards

Choose a number line or hundred square to support adding or subtracting two-digit numbers
Select a ruler when a problem requires measuring length
Explain why one representation (e.g. a number line vs cubes) is more helpful for a particular problem

The lesson

Not every problem is best solved in your head. A number line, a hundred square, or a ruler can help you see the answer instead of guessing.

A number line helps you hop from one number to another, like hopping from 24 to 34 by adding 10.

Tap to fill the grid, one at a time: 10 rows of 10.

A hundred square has 100 boxes in rows of ten. It helps you count on quickly, like a number line laid flat.

Try it together

Mia needs to measure her book, so she picks up a ruler, not a number line, because a ruler is made for measuring length. Then Mia needs to add 36 and 20, so she picks a hundred square and counts on two rows. She chose a different tool for each job.

Good to know

Ask yourself: am I measuring something, or am I adding and subtracting numbers? That tells you which tool to reach for.

Pick the tool that matches the problem: a ruler for length, a number line or hundred square for adding and subtracting.

Watch it

Where it sits

Learn first

Hands-On Problem Solving Measuring length (age 6+)Adding within 100

This opens up

Choosing the right strategy

Where this leads

Jobs that lean on this skill. Follow one to see everything it is built on.

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Then practise

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.