Year 6: Reading and drawing line graphs
Part of the Year 6 pie charts, line graphs and the mean chapter. Chapter overview · whole chapter on one page
Reading and drawing line graphs
A line graph shows how a value changes over time. A point is marked for each time, day, month or week. The points are joined with straight lines. The bottom of the graph shows the time, and the side shows the value and its units.
To read a value, find the label along the bottom, go straight up to the point, and then go across to the scale. To draw a line graph, choose a scale that fits all your values. Each square should be worth the same amount. Plot each point carefully, then join the points in order with a ruler.
If the graph has numbered points, you can write the point as coordinates. The first number is the point number from the left, and the second number is its value.
Key ideas
- Read the point, not the line between two points.
- Each square on the scale is worth the same amount. Count the steps, not the lines.
- To draw a point, count up the scale from zero to find the number of squares.
- Join the points in order from left to right, with straight lines.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Find the label, go up to the point, then go across to the scale.
- Find the time or week along the bottom. Find Apr on the horizontal line.Apr
- Go up to the line. Go straight up from the label to the point. Do not read the line between two points.the point for Apr
- Go across to the scale. Read the number on the scale level with the point. The scale is in mm.Rainfall in April = 20
Check. The point sits on a gridline, so the reading is exact. ✓
Watch out. Read the point itself. A line between two points only shows the change.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Use the position of the point for the across number and its value for the up number.
- Number the points from left to right. Start counting at 1 for the first point.Jun is point number 6
- Read the value on the scale. This is the up number, the value on the scale for that point.value = 70
- Write the coordinates. Write the point number first, then the value.(6, 70)
Check. Counting 6 points from the left reaches Jun, and its value is 70. ✓
Watch out. Write the position first, then the value. Do not swap them.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Divide the value by the value of one square on the scale.
- Write the value to draw. The money raised in Week 5 is the value we need to plot.The money raised in Week 5 = 60
- Write the value of one square. Each square on the scale goes up by this much.1 square = 10
- Count the squares from zero. Divide the value by the value of one square.60 ÷ 10 = 6
Check. 6 squares of 10 make 60. ✓
Watch out. Count the steps on the scale, not the lines. Each square is worth the same amount.
Watch out
Common mistake: reading the value from the bottom instead of the side. Go up from the time to the point, then across to the scale. Another mistake is to count the lines as one unit each, when each step on the scale may be worth 10 or 20.
Exercise 12D Practice: reading and drawing line graphs
Non-calculatorKey words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Find the label, go up to the point, then go across to the scale.
- Find the time or week along the bottom. Find Mar on the horizontal line.Mar
- Go up to the line. Go straight up from the label to the point. Do not read the line between two points.the point for Mar
- Go across to the scale. Read the number on the scale level with the point. The scale is in mm.Rainfall in March = 30
Check. The point sits on a gridline, so the reading is exact. ✓
Watch out. Read the point itself. A line between two points only shows the change.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Find the point at that height, then go down to the label along the bottom.
- Find the value on the scale. Find the level of 50 on the scale.50
- Go along the line to that point. Find the point at this level, then go down to the bottom of the graph.the point at 50
- Read the label along the bottom. This is the time or week for the rainfall of 50 mm.May
Check. Only May reaches 50. ✓
Watch out. Start from the value on the scale, not from the bottom. Check the other points too.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Find the label, go up to the point, then go across to the scale.
- Find the time or week along the bottom. Find Week 4 on the horizontal line.Week 4
- Go up to the line. Go straight up from the label to the point. Do not read the line between two points.the point for Week 4
- Go across to the scale. Read the number on the scale level with the point. The scale is in £.Money raised in Week 4 = 70
Check. The point sits on a gridline, so the reading is exact. ✓
Watch out. Read the point itself. A line between two points only shows the change.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Find the label, go up to the point, then go across to the scale.
- Find the time or week along the bottom. Find 12:00 on the horizontal line.12:00
- Go up to the line. Go straight up from the label to the point. Do not read the line between two points.the point for 12:00
- Go across to the scale. Read the number on the scale level with the point. The scale is in %.Battery at 12:00 = 60
Check. The point sits on a gridline, so the reading is exact. ✓
Watch out. Read the point itself. A line between two points only shows the change.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Divide the value by the value of one square on the scale.
- Write the value to draw. The money raised in Week 2 (£) is the value we need to plot.The money raised in Week 2 (£) = 50
- Write the value of one square. Each square on the scale goes up by this much.1 square = 10
- Count the squares from zero. Divide the value by the value of one square.50 ÷ 10 = 5
Check. 5 squares of 10 make 50. ✓
Watch out. Count the steps on the scale, not the lines. Each square is worth the same amount.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Divide the value by the value of one square on the scale.
- Write the value to draw. The battery at 14:00 is the value we need to plot.The battery at 14:00 = 40%
- Write the value of one square. Each square on the scale goes up by this much.1 square = 20%
- Count the squares from zero. Divide the value by the value of one square.40 ÷ 20 = 2
Check. 2 squares of 20% make 40%. ✓
Watch out. Count the steps on the scale, not the lines. Each square is worth the same amount.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Use the position of the point for the across number and its value for the up number.
- Number the points from left to right. Start counting at 1 for the first point.Mar is point number 3
- Read the value on the scale. This is the up number, the value on the scale for that point.value = 30
- Write the coordinates. Write the point number first, then the value.(3, 30)
Check. Counting 3 points from the left reaches Mar, and its value is 30. ✓
Watch out. Write the position first, then the value. Do not swap them.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Find the highest point, and read its label along the bottom.
- Read every point on the graph. Look at the height of each point.Jan 60, Feb 40, Mar 30, Apr 20, May 50, Jun 70
- Find the highest point. The highest point has the biggest value.highest value = 70
- Write the answer. This is the label for that point.Jun
Check. No other point is higher than 70. ✓
Watch out. Check every point, including the first and the last.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Find the lowest point, and read its label along the bottom.
- Read every point on the graph. Look at the height of each point.Jan 60, Feb 40, Mar 30, Apr 20, May 50, Jun 70
- Find the lowest point. The lowest point has the smallest value.lowest value = 20
- Write the answer. This is the label for that point.Apr
Check. No other point is lower than 20. ✓
Watch out. Check every point, including the first and the last.
Key words. The change is how much a value has gone up or down. To find it, take the first value away from the second value.
Method. Read both values, then take the smaller one away from the bigger one.
- Read the first value. January is 60 mm.January = 60
- Read the second value. February is 40 mm.February = 40
- Find the difference. January is the bigger, so take the smaller value away.60 − 40 = 20
- Write the answer. 20
Check. 40 + 20 = 60, so the difference is right. ✓
Watch out. Subtract the smaller value from the bigger value. The answer is never negative.
Key words. A line graph marks a point for each time or week, and joins the points with straight lines. The scale is the numbers up the side. The lines across the graph are the gridlines.
Method. Check every pair of neighbouring months, not only the first and last.
- Read the rainfall for each month. Read each point in order, from January to June.Jan 60, Feb 40, Mar 30, Apr 20, May 50, Jun 70
- Look at each pair of months. Check whether each month is less than the month before.Jan to Feb: down; Feb to Mar: down; Mar to Apr: down; Apr to May: up
- Decide. One rise is enough to show the statement is not true.No
Check. April 20 mm to May 50 mm is a rise of 30 mm, so the rainfall did not fall every month. ✓
Watch out. A line that falls for most of the graph can still rise once. Check every pair.
Watch out
Watch out: check the scale before you read. A scale may go up in steps of 2, 5, 10 or 20, so one square is not always one unit.
Exam tip
When you draw a line graph, use a ruler for the lines and check each point against the table before you join them.