Putting the Number Line Online

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As a primary teacher, I use number lines all the time.

Whether I’m teaching the four operations, place value, rounding, negative numbers, decimal numbers or fractions: number lines are the go-to tool for developing a conceptual understanding of numbers.

The problem is: each teaching objective requires a different type of number line, and printed number lines are limited by their length, range, and intervals. They just aren’t flexible enough!

This is why we decided to build an app: numberline.school is a zoomable, infinite number line which can be flexibly used to teach maths in any classroom.

Why numberline.school

It's not just saving paper.

Thanks to it being a digital app, you can scroll infinitely along the number line — both into negative and very large positive numbers.

The zooming function allows you to easily zoom in to the decimals, and out to the millions — giving the user a flexible overall understanding of a number line.

The scale is animated and shows the appropriate power of 10 as you zoom: counting first in ones, then tens, hundreds, thousands, ten thousands, hundred thousands and up to hundred millions. In decimal places, it can count in tenths, hundredths, and thousandths.

How to Use The Number Line

numberline.school runs on any computer. But it works best on touch screen devices such as iPads, tablets, or smartphones as the touch gestures allow for zooming and scrolling.

Teachers can, for instance, project the number line to a whiteboard and use it to model to students. If enough devices are available, all students can use it for a lesson, or it may become a favourite scaffolding tool for any students with SEN.

You can also mark numbers with pins . Pins are unlimited and can be placed absolutely anywhere along the number line. This way, students can pin a number and then zoom in or out to view where the number is in relation to others - perfect for rounding!

Students really enjoy the number line app and even just playing around with it inspires a sense of awe about the sheer infinity of the number world. They can see just how big numbers get, but also discover more rarely used numbers such as large decimal numbers.

Often kids are stumped when they see a large number with decimal places such as 30,000.25.

With a Touchscreen...

• Swipe left and right to scroll along the infinite number line.
• Pinch to zoom in and out to see the number line count in tens, hundreds, thousands,…
• Place an unlimited amount of coloured pins by clicking, dragging, and then releasing them on the number line. If you let go over a labelled number, the pin will snap into position.
• Tap the reset button to centre the number line on zero and delete all pins.

With a Mouse...

• Click and drag left and right to scroll along the infinite number line.
• Click the magnifying glass icons to zoom in and out between tens, hundreds, thousands,…
• Place an unlimited amount of coloured pins by pressing, dragging, and then releasing them on the number line. If you let go over a labelled number, the pin will snap into position.
• Click the reset button to centre the number line on zero and delete all pins.

Six Educational Ways to use The Number Line

1. Consolidate Place Value

A great way to give students a sense for place value is to let them simply play around with the number line. This could even be a warm-up starter activity for a lesson, and students often really enjoy playing with it.

Some questions you could ask to lead the activity:

2. Find the Number!

Whether students are learning about negative numbers, decimals, or large numbers, writing a number down is often very different from actually understanding what the number means on the big number continuum.

You can make it a game to see which pair of students can find a number the fastest.

3. Understand Rounding to the Nearest Power of Ten

Rounding was the main inspiration for making this number line app: every year, I find students have forgotten how to round to the nearest ten, hundred, or thousand — no matter how well they knew it the year before.

To me, this was a clear sign that students are lacking the conceptual understanding of rounding. You may have heard and used the countless mnemonics which have been created to help students remember how to round:

“Five or more, raise the score, four or less, let it rest”
“five or more, let it soar”
“five and above, give it a shove”

These are just some of the most popular ones. However, none of the mnemonics help students understand why they can simply “raise the score”.

In contrast, number lines are a great way to visualise how rounding works. And, thanks to its flexibility, numberline.school is an excellent tool for showing rounding to the nearest 10/100/1,000 — or even higher powers of ten.

Here’s how:

Ask the children to show you a number line which is counting in tens/multiples of ten (and clarify that even in 6-digit numbers you can still count up in tens!). Can they show the same for counting in hundreds, thousands, ten thousands?

Ask them to find a number (e.g. 4972) and place a pin on it:

Now have them zoom out until they see the tens. They should now be able to see which “ten” it is closest to, i.e. when rounding to the nearest ten, it should round to 4970…

… then, by simply zooming further out, repeat for rounding to the nearest 100…

… rounding to the nearest 1,000…

… and so on!

4. Estimating Numbers on a Number Line

One of the main stepping stones of understanding place value is being able to estimate the position of different numbers on a number line in relation to other numbers. For instance, where is 150,000 in relation to 15,000 or 50,000? Using the screenshot tools, teachers can easily create simple worksheet challenges to print out for students. Simply pin certain numbers with different colours (this can be differentiated according to students’ needs) and ask students to label the pins.

As shown in the example below, students could have the task to estimate numbers shown by pins - either freely, or as multiple choice answers.

5. Ordering Numbers

Whether ordering positive and negative integers or ordering decimals, having a number line to visualise the numbers is vital.

With numberline.school, students can visually compare the sizes of different numbers. The zooming and scrolling give a real sense of scale.

6. Visualising Addition and Subtraction

For simple additions and subtractions, number lines let you “count the jumps” between numbers.

By practicing addition and subtraction on a number line, children will internalise it and be able to remember it when doing mental maths.

Examples:

Alternatively, they can prove that subtractions are the same as finding the difference between two numbers: ask students to place a pin on 23 and on 15 and to count how many jumps difference it is - it should be the same answer!

Number lines can be extremely helpful in teaching addition and subtraction with negative numbers! Students can scroll across zero to help them count and find the difference between -3 and 7 for example.

I hope you find this number line as useful as I do — many of my students now beg me to use numberline.school!