Chapter 3 of 7

All 7 chapters
  1. 1Tally and frequency tables, readunderstood
  2. 2Pictograms with a key, readunderstood
  3. 3Bar charts, readunderstood
  4. 4Tables with rows and columns, readunderstood
  5. 5Sorting diagrams, readunderstood
  6. 6Line graphs, readunderstood
  7. 7Your own survey, readunderstood

M2.7.3 Chapter 3

Bar charts

The bar for Ball reaches the third line above 0. Is Ball 3?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

  • You picked A. Read on. At the end, the chapter comes back to your guess.

  • You picked B. Read on. At the end, the chapter comes back to your guess.

  • You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

  • Draw a bar chart with a scale going up in 5s
  • Read a bar chart to compare groups

Mei asks 50 children for their best game. She counts each answer.

A bar chart shows each count as a bar. A taller bar means more.

The scale is the row of numbers up the side. Here it goes up in 5s.

A scale starts at 0. It goes up by the same amount every time.

Draw it first

Draw a bar chart of the games

  1. A bar chart of favourite games with the label children. The bars are Tag, Ball, Rope and Kite. The scale goes 0, 5, 10, 15, 20, 25. Tag reaches 20, Ball 15, Rope 10 and Kite 5.0510152025TagBallRopeKitechildren

    1 Draw a line up the side. Write 0 at the bottom. Then 5, 10, 15, 20 and 25.

  2. A bar chart of favourite games with the label children. The bars are Tag, Ball, Rope and Kite. The scale goes 0, 5, 10, 15, 20, 25. Tag reaches 20, Ball 15, Rope 10 and Kite 5.0510152025TagBallRopeKitechildren

    2 Tag has 20. Draw a bar up from 0 to the line for 20.

  3. A bar chart of favourite games with the label children. The bars are Tag, Ball, Rope and Kite. The scale goes 0, 5, 10, 15, 20, 25. Tag reaches 20, Ball 15, Rope 10 and Kite 5.0510152025TagBallRopeKitechildren

    3 Ball has 15 and Rope has 10. Draw bars of the same width.

  4. A bar chart of favourite games with the label children. The bars are Tag, Ball, Rope and Kite. The scale goes 0, 5, 10, 15, 20, 25. Tag reaches 20, Ball 15, Rope 10 and Kite 5.0510152025TagBallRopeKitechildren

    4 Kite has 5. Draw the last bar. Write each name under its bar.

To read a bar, find the top of it. Look across to the scale.

Worked example

How many children chose Rope?

  1. Find the Rope bar.
  2. Look at the top of the bar. Read across to the scale.
  3. The top is at 10.

Answer: 10 children

Worked example

How many more children chose Tag than Kite?

  1. Tag reaches 20. Kite reaches 5.
  2. Take the smaller from the bigger. 20 − 5 = 15.

Answer: 15 more children

Worked example

How many children did Mei ask?

  1. Add the four bars. 20 + 15 + 10 + 5.
  2. 20 + 15 = 35. 35 + 10 = 45. 45 + 5 = 50.

Answer: 50 children

See it three ways

With things

Put 15 beans in lines of 5. You make 3 lines.

As a picture

Fifteen beans in 3 lines of 5. Beside them is a bar chart with the label children and one bar, Ball. The scale goes 0, 5, 10, 15, 20 and the bar reaches 15.05101520Ballchildren

In symbols

3 × 5 = 15. The bar climbs 3 jumps of 5. It stops at 15.

Try it

Ask people and draw a bar chart

You need: a pencil and paper, a few people to ask.

  1. Ask people which they like best: rice, bread or beans. Make a tally.
  2. Draw a line up the side. Start at 0 and go up in 5s.
  3. Draw one bar for each food. Make the bars the same width.
  4. Stop each bar at its frequency. Write each name under its bar.

What you will see: The tallest bar is the food most people chose. If a count is between two lines, stop the bar between them.

If you cannot try it, this is what happens.
A bar chart of favourite foods with the label people. The bars are Rice, Bread and Beans. Rice reaches 10, Bread 15 and Beans 5.05101520RiceBreadBeanspeople

A wrong idea many people have

A bar that reaches the third line above 0 is worth 3.

Why it feels right: In many charts the lines go 1, 2, 3. Counting lines works there.

The test that breaks it: Look at the numbers beside the lines. They go 0, 5, 10, 15. Put out 3 lines of 5 beans and count them. You get 15, not 3.

What is true: Read the number beside the line. On a scale in 5s, the third line above 0 is 15.

Key words

bar chart
a chart that shows each count as a bar.
scale
the numbers up the side of a chart.

Back to your guess

The answer is B: No. I read the number on the scale where the bar stops.

Read the number written beside the line where the bar stops. The scale goes up in 5s. The third line above 0 is 15, not 3.

Check yourself

Try each one before you look. A wrong answer tells you where to go next.

  1. How many ducks are on the farm?

    A bar chart of animals on a farm, with the label animals. The bars are Cows, Hens, Goats and Ducks. The scale goes up in 5s.0510152025CowsHensGoatsDucksanimals
    Tap your answer.

    1. Not this one. You counted the lines. The scale goes up in 5s, so read the number: 15. Try another.

    2. Yes, that is right. The top of the Ducks bar is at the line marked 15.

    3. Not this one. 25 is the Hens bar. Ducks is the bar on the right, and it is shorter. Try another.

    See the answer

    15

    The top of the Ducks bar is at the line marked 15.

    • If you chose A: You counted the lines. The scale goes up in 5s, so read the number: 15.
    • If you chose C: 25 is the Hens bar. Ducks is the bar on the right, and it is shorter.

  2. Which animal is there the most of?

    A bar chart of animals on a farm, with the label animals. The bars are Cows, Hens, Goats and Ducks. The scale goes up in 5s.0510152025CowsHensGoatsDucksanimals
    Tap your answer.

    1. Not this one. Cows is the first bar, but it is the shortest. The tallest bar is the most. Try another.

    2. Not this one. Ducks is the last bar. The last bar is not always the tallest. Compare the heights. Try another.

    3. Yes, that is right. The Hens bar is the tallest. It reaches 25.

    See the answer

    Hens

    The Hens bar is the tallest. It reaches 25.

    • If you chose A: Cows is the first bar, but it is the shortest. The tallest bar is the most.
    • If you chose B: Ducks is the last bar. The last bar is not always the tallest. Compare the heights.

  3. How many more ducks than goats are on the farm?

    A bar chart of animals on a farm, with the label animals. The bars are Cows, Hens, Goats and Ducks. The scale goes up in 5s.0510152025CowsHensGoatsDucksanimals
    See the answer

    5

    Ducks are 15 and goats are 10. 15 − 10 = 5.

  4. How many animals are on the farm in all?

    A bar chart of animals on a farm, with the label animals. The bars are Cows, Hens, Goats and Ducks. The scale goes up in 5s.0510152025CowsHensGoatsDucksanimals
    See the answer

    55

    Add the four bars. 5 + 25 + 10 + 15 = 55.

  5. Draw a chart of rice 15, bread 10 and maize 20. What scale do you use?

    See the answer

    Start at 0. Go up in 5s: 0, 5, 10, 15, 20. The bars stop at 15, 10 and 20.

    Every count is in the 5 times table. The biggest is 20. A scale in 5s up to 20 fits them all.

  6. From an earlier chapter

    In a pictogram each circle is 2. A row has 4 circles and half a circle. How tall is its bar?

    See the answer

    9

    Four circles are 4 × 2 = 8. Half a circle is 1. 8 + 1 = 9.

  7. How many books did Hana read?

    A bar chart of books read, with the label books. The bars are Hana, Diego, Priya and Yusuf. The scale goes up in 2s.024681012HanaDiegoPriyaYusufbooks
    Tap your answer.

    1. Yes, that is right. The top of the Hana bar is on the line marked 6. The scale goes up in 2s: 0, 2, 4, 6.

    2. Not this one. You counted the lines. This scale goes up in 2s. Read the number beside the line. Try another.

    3. Not this one. You read the next line up. The top of the Hana bar stops on the line marked 6. Try another.

    See the answer

    6

    The top of the Hana bar is on the line marked 6. The scale goes up in 2s: 0, 2, 4, 6.

    • If you chose B: You counted the lines. This scale goes up in 2s. Read the number beside the line.
    • If you chose C: You read the next line up. The top of the Hana bar stops on the line marked 6.

  8. How many seeds sprouted in all?

    A bar chart of seeds that sprouted, with the label seeds. The bars are Bean, Maize, Pea and Lentil. The scale goes up in 5s.05101520BeanMaizePeaLentilseeds
    Tap your answer.

    1. Not this one. That counts the bars. Read each bar and add them. Try another.

    2. Not this one. That is the tallest bar, for Lentil. The total needs every bar added. Go to M2.7.1. Try another.

    3. Yes, that is right. Add the four bars. 10 + 5 + 15 + 20 = 50.

    See the answer

    50

    Add the four bars. 10 + 5 + 15 + 20 = 50.

    • If you chose A: That counts the bars. Read each bar and add them.
    • If you chose B: That is the tallest bar, for Lentil. The total needs every bar added. Go to M2.7.1.

  9. Kofi writes a scale for his chart. It reads 0, 5, 10, 20, 25. What is wrong?

    Tap your answer.

    1. Not this one. A scale starts at 0. A bar with nothing in it is at 0. Try another.

    2. Yes, that is right. The jumps should all be 5. Between 10 and 20 the scale needs 15.

    3. Not this one. The jumps are not the same. 5 to 10 is a jump of 5. 10 to 20 is a jump of 10. Try another.

    See the answer

    It skips 15. A scale goes up by the same amount each time.

    The jumps should all be 5. Between 10 and 20 the scale needs 15.

    • If you chose A: A scale starts at 0. A bar with nothing in it is at 0.
    • If you chose C: The jumps are not the same. 5 to 10 is a jump of 5. 10 to 20 is a jump of 10.

Keep it

Copy this into your exercise book.

A scale starts at 0 and goes up evenly, here in 5s. Read the number beside the top of the bar. Do not count lines. A taller bar means more.

Draw: A bar chart with three bars. Write the scale 0, 5, 10, 15.

Reading with a child? A short page for the adult: what this chapter teaches and three questions to ask.

No internet tomorrow? Save the whole book as one file (828 KB). It opens on any phone.