Mathematics

Intermediate

50 mins

Teacher/Student led

Learning Goals

Learning Outcomes

Lesson Files

+65 XP

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Making a Bar Chart with a Chosen Scale

Build a bar chart by choosing a scale that fits your largest value, drawing equal-width bars, and reading heights accurately from the scale lines.

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1 Getting Started
2 Watch and Notice
3 Try It Together
4 Draw the Axes in Your Copy
5 Class Challenge
Pupil practice

1 - Getting Started ~4 mins

Illustration for Getting Started We asked the class to vote for their favourite GAA county. Hands up: how could we show all those votes so the whole class reads them at a glance? And what would a taller bar mean?

Teacher Notes

Take three hands-up answers, not open call-outs. Steer toward taller bar means more votes without confirming yet — that is what the lesson builds.

👇 Mark your steps as done as you complete them.

+5 XP

2 - Watch and Notice ~10 mins

Watch these charts of our favourite-county votes. The first two show 6 votes drawn two different ways: once on a scale marked in 1s, once on a scale marked in 2s. Notice the second bar climbs half as many steps but stands for the same 6. Then watch two counties added side by side. Look at the last two charts carefully: the same two counties, 14 votes and 18 votes, are drawn first on a scale of 2 and then on a scale of 5. On the scale of 2 you can clearly see one bar is taller. On the scale of 5 the two bars look almost the same height, even though the votes have not changed.

Teacher Notes

Point to the two 6-bars side by side: same amount, different scale. Ask what stayed the same before revealing.

On the scale-of-2 bar, run a finger from the bar top across to the 6 line so pupils see you read the scale, not count steps.
Hold the last two charts side by side. Ask which county got more votes? on the scale of 2 (easy to see), then ask the same on the scale of 5 (much harder). Name it out loud: a scale that is too big can hide a real difference. This is the picture the class will come back to at the end.
Watch for pupils who think the scale-of-1 bar means more because it is taller; it is not — it is the same 6.

👇 Mark your steps as done as you complete them.

+10 XP

3 - Try It Together ~8 mins

Here is a sample set of lunch choices for our next chart. First we choose a scale that lets the biggest value fit. The biggest value is 12: a scale of 2 fits it in six steps (0, 2, 4, 6, 8, 10, 12); a scale of 1 would fit it too but in twelve steps, which is a lot of lines to mark. A scale of 2 is our choice. Then set each bar to the right height and check every bar is the same width:

Sandwich: 12
Pasta: 6
Salad: 4
Wrap: 8

Our lunch choices

Teacher Notes

Talk this one through together — pupils take turns at the board and the class agrees or corrects out loud.

Agree the scale of 2 out loud before anyone drags a bar; ask would a scale of 1 still fit? how many more lines would we have to mark?

Rotate four pupils, one per lunch choice. Each time, have the pupil drag the bar top to the scale line, not guess a spot between lines. The class calls whether the height matches the value.

+15 XP

4 - Draw the Axes in Your Copy ~5 mins

COPYBOOK MOMENT

Illustration for Draw the Axes in Your Copy In your maths copy on squared paper, draw and label the two axes. Mark the scale up the side in 2s (0, 2, 4, 6...). If you have time, draw the first bar from the class data to the right height.

Teacher Notes

Walk the room glancing for two labelled axes and a scale marked in even 2s up the side. If a pupil gets a bar drawn too, check its top lands on a scale line and its width matches the squares. No individual marking — this is whole-class copybook practice, not assessment.

+10 XP

5 - Class Challenge ~9 mins

Now we build these charts on the board, and the first job every time is to choose the scale. The biggest value in our full set is 20. Which scale should we mark up the side? Decide together, then build: first a bar to a value of 6, then a bar to 12, then a bar to 18, and last a full set of four bars — 8, 14, 6, 20. Every value here is even, so each bar top lands exactly on a marked line.

Build the bars

Teacher Notes

This is the practice round — pupils take turns at the board, check each answer, and the class confirms before moving on. Keep the board work brisk rather than over-explaining.

Do the scale choice first, out loud, as a real decision: ask the biggest value is 20 — does a scale of 2 reach it? how many lines? Only once the class agrees a scale of 2 fits do you start building bars.
Ask the class to predict which line each bar top will land on before the pupil drags it.
Watch for bar tops landing between lines, and for uneven bar widths.

+15 XP

Pupil practice

Module 9 · Data and Chance Mixed

Lesson 105 · Making a Bar Chart with a Chosen Scale

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Making a Bar Chart with a Chosen Scale

Teacher Class Feed

1 - Getting Started ~4 mins

2 - Watch and Notice ~10 mins

3 - Try It Together ~8 mins

Our lunch choices

4 - Draw the Axes in Your Copy ~5 mins

5 - Class Challenge ~9 mins

Build the bars

Unlock the full learning experience

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