Myriora Maths › Maths foundations › Chapter 1: Numbers and place value
The number line
Ages 5–7Chapter 1 · Lesson 4✓ Watched
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Practise
Ten new questions every time. Answer them all, then check: you get your score, and the working for anything you missed.
In this lesson
- Numbers on a line are in order, and evenly spaced.
- Adding means jumping to the right, and taking away means jumping to the left.
- And count the jumps, not the numbers.
Your turn
On a line from zero to twenty, which number goes in the middle?
Show the answer
Ten is half of twenty, so it goes right in the middle. It's ten!
The common mistake
Here's a question that catches lots of people. How many jumps is it from three to seven? Some people count the numbers they touch: three, four, five, six, seven, and say five. But count the jumps instead: one, two, three, four. Four jumps!
Try it at home
Use a ruler or tape measure as a number line: "Find 13. How many jumps to 20?"
The one-minute version
Read the whole lesson
Hello, and welcome to Myriora Maths! Today, let's meet one of the most useful pictures in all of maths: the number line.
Why use a number line? Think of a ruler, or a tape measure. Or the buttons in a lift. They're all number lines! They help us see where numbers are, and how far apart they are.
A number line has numbers in order, evenly spaced. Every step is the same size. Bigger numbers are further to the right.
We can add by jumping. Start at three, and jump on four times: four, five, six, seven. Three plus four is seven!
To take away, we jump the other way: to the left. Seven take away two. Start at seven, and jump back two: six, five. Seven take away two is five!
Let's try one together. Start at five, and jump three to the right. Where do you land? Say it out loud!
Six, seven, eight. We land on eight! Five plus three is eight. Well done if you said eight!
Some number lines only show the ends. Where does fifty go, on a line from zero to a hundred? Fifty is half of a hundred, so it goes right in the middle! And twenty-five is half of fifty, so it's halfway to the middle.
Here's a question that catches lots of people. How many jumps is it from three to seven? Some people count the numbers they touch: three, four, five, six, seven, and say five. But count the jumps instead: one, two, three, four. Four jumps!
Your turn! On a line from zero to twenty, which number goes in the middle? Pick the right card. You've got fifteen seconds, or pause the video. Go!
Time's up! Ten is half of twenty, so it goes right in the middle. It's ten!
Quick review. Numbers on a line are in order, and evenly spaced. Adding means jumping to the right, and taking away means jumping to the left. And count the jumps, not the numbers. See you next time!
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