Bar charts and line charts
Bar charts and line charts
A bar chart draws a frequency table: a bar for each answer, and the bar’s height is the answer’s frequency.
This is class 6B’s table of pets, as a chart:
- The horizontal axis: the answers – here, the pets.
- The vertical axis: the frequency – the number of pupils, in equal steps: 0, 2, 4, …
- The tallest bar is the most frequent answer: dog.
- All the bars are the same width, with gaps between them.
A line chart shows how something changes over time: a point for each time, and a line joining the points in order.
These are the rainy days in the town in each month of last winter:
- From November to January the line goes up: each month had more rainy days than the month before.
- From January to March the line goes down: there were fewer and fewer rainy days.
- The steepest piece is the biggest change: from November to December, more rainy days.
- A line chart fits when the answers are times in a fixed order: days, months, years. Pets have no such order, so they get a bar chart.
A bar chart is drawn from a frequency table in four steps:
- Draw two axes: the horizontal one for the answers, the vertical one for the frequencies.
- Choose a step for the vertical axis, so that even the largest frequency fits. For the pets the largest frequency is 9, so a step of 2, up to 10.
- Draw a bar for each answer, up to the height of its frequency. All the bars are the same width.
- Write the answer under each bar, and a title on each axis.
The chart shows how the pupils of class 6D get to school.
Which way is the most frequent, and which is the least frequent?
How many pupils are there in the class?
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
How many more pupils walk than come by car?
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
Noa planted a sunflower, and measured its height at the end of each week.
How tall was the sunflower at the end of the fourth week?
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
By how many centimetres did the sunflower grow from the end of the first week to the end of the sixth?
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
In which week did the sunflower grow the most? How can you see it in the chart?
26 pupils chose their favourite fruit.
| Fruit | apple | banana | grapes | watermelon |
|---|---|---|---|---|
| Frequency | 6 | 9 | 4 | 7 |
Draw a bar chart of the table.
Choose a good step for the vertical axis.
Which chart fits each set of data – a bar chart or a line chart? Explain.
- The temperature at noon on each day of one week.
- The favourite colour of the pupils in the class.
- The number of pupils in each of the school’s sixth-grade classes.
- A puppy’s weight, measured once a month in its first year.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power