1. Mathematics Lesson 3: Line graphs

2. how to interpret the information in line graphs
Learning Intentions
We are learning…
about line graphs, their features and the types of data that suit line graphs
how line graphs can provide information about many different areas of life, including other subject areas
how to interpret the information in line graphs
AfL
Share these AfL learning intentions with pupils in your introduction to the lesson.
Share and negotiate success criteria with pupils.

3. Temperature in Belfast over a 24 hour period
AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection by asking for feedback from pupils.
Possible discussion points
Describe how the temperature has changed over the 24 hour period.
What time of year do you think these temperatures were recorded?
Can you say what the temperature was at, say, 3.30 pm?

4. Line graphs
A line graph usually shows how something changes in value as time goes by.
The data is plotted as points and these points are joined by straight lines.
Time is always on the horizontal axis.
The lines joining the points can be used to estimate values between the points.
Give pupils a copy of Resource 3, which shows the temperature graph from the previous slide.
Use this temperature graph to illustrate each of the points on the slide.

5. Interpreting line graphs – useful phrases
Work in pairs to complete Worksheet 3a.
AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection
by asking for feedback from pupils; and
by encouraging peer and self-assessment.
Thinking Skills and Personal Capabilities
In Worksheet 3a, pupils have the opportunity to develop the following skill:
Managing Information.
Distribute Worksheet 3a. Ask pupils to work in pairs.
Discuss the words or phrases on the worksheet that pupils will use to describe each graph, such as ‘rapidly’, ‘steadily’, ‘increasing’ and ‘decreasing’.
Ask pupils to look at each graph and create sentences to describe each graph. They should match the appropriate phrases on the worksheet with each graph. Let them know that they can use more than one phrase if appropriate to describe a graph.
Ask them to concentrate on the shape of the graph rather than the actual numbers on the y-axis.

6. Value of Niamh’s car AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection
by asking for feedback from pupils.
Possible discussion points
Would a bar chart be an effective way to show this information? If not, why not?
Why would Niamh want to know the value of her car every 6 months?
Describe how the value is decreasing. Encourage pupils to use the same language as in Worksheet 3a when talking about information on both axes of the graph.
What do you think will happen to the value of the car as time goes on?

7. Value of Niamh’s car – model answer
In the first year, the value of Niamh’s car decreases sharply. After that, the value continues to decrease, but at a much slower rate.
The value decreases by about £4000 in the first year but by only £700 over the next year.
AfL
This part of the lesson uses the following strategy:
scaffolding reflection
by encouraging peer and self-assessment.
The slide shows a model answer to the graph question on the previous slide.
Explain to pupils that a few bullet points are enough to answer the question. There is no need for them to write a lengthy description.

8. Line graphs activity Now complete Worksheet 3b: More Line Graphs AfL
This part of the lesson uses the following strategies:
effective questioning; and
scaffolding reflection
by asking for feedback from pupils; and
by encouraging peer and self-assessment.
Thinking Skills and Personal Capabilities
In Worksheet 3b, pupils have the opportunity to develop the following skills:
Thinking, Problem-Solving and Decision-Making;
Managing Information; and
Being Creative.
Give pupils copies of Worksheet 3b and ask them to complete it.