Line graphs

Quick answer

A line graph is a way to show how something changes over time, using points connected by lines. You can see patterns and trends by looking at the shape of the line.

Learning outcome

By the end of this page, you will be able to read and draw line graphs to show how data changes over time.

• You can identify the start and end points on a line graph.
• You can explain what a rising or falling line means.
• You can plot points and connect them to make a line graph.
• You can use a line graph to find out information about changes over time.

Why this matters

Line graphs help us see how things change over time, like your height growing, how many books you read each month, or how the temperature changes during the day. They are used in science, sports, weather, and even in games and cooking. Understanding line graphs helps you make sense of information and see patterns that might not be obvious in a list of numbers.

How it works

Line graphs have two axes: the horizontal axis (x-axis) usually shows time, and the vertical axis (y-axis) shows the amount or value. Points are placed on the graph to show data, and lines connect these points to show how the data changes over time.

1. Draw two axes, one horizontal (x-axis) and one vertical (y-axis).
2. Label the x-axis with time (like days, months, or hours).
3. Label the y-axis with the values you are measuring (like temperature, height, or number of items).
4. Plot points at the correct time and value.
5. Connect the points with straight lines.

Examples you can see

Let’s imagine you are tracking how much your plant grows each week. Here’s how you would make a line graph:

Now, you would:

1. Draw the x-axis with weeks 1 to 4.
2. Draw the y-axis with heights from 0 to 15 cm.
3. Plot points at (1,5), (2,7), (3,9), and (4,12).
4. Connect the points with lines.

You can see that the plant grows steadily over time. The line goes up, which means the plant is growing.

Try it as a mini adventure

Imagine you are a weather reporter for a week. You have to track the temperature each day and make a line graph to show how it changes.

Day 1: 10°C

Day 2: 12°C

Day 3: 8°C

Day 4: 15°C

Day 5: 13°C

Day 6: 11°C

Day 7: 9°C

Your mission: Draw a line graph showing these temperatures. Use the x-axis for days and the y-axis for temperature in degrees Celsius.

How does the line look? Does it go up and down? What does this tell you about the weather?

Common mistakes

• Mistake: Not connecting the points with lines.
  Why it happens: Forgetting that a line graph shows the change over time.
  Fix: Always connect the points with straight lines to show the pattern.
• Mistake: Not labelling the axes.
  Why it happens: Thinking the graph is obvious without labels.
  Fix: Always write what each axis shows (like "Days" and "Temperature in °C").
• Mistake: Plotting points in the wrong place.
  Why it happens: Confusing the x and y values.
  Fix: Double-check that the point matches the correct time and value.
• Mistake: Drawing the lines too curvy.
  Why it happens: Thinking the line should look like a wave.
  Fix: Keep lines straight between points to show the actual change.

Parent and carer guide

Helping your child with line graphs is simple and fun! Here’s how to support them in just 5–10 minutes:

• Ask your child to explain what the graph shows. They might say, "This line goes up, so the temperature is getting warmer."
• Use everyday examples like tracking how much you grow each year or how many books you read each month.
• Encourage them to look at the shape of the line: Does it go up? Down? Flat? What does that mean?
• Make a graph together using their own data. For example, draw a line graph of how many toys they have each month.
• Don’t worry if they make a mistake. Use it as a learning moment to talk about what went wrong and how to fix it.

Remember: Line graphs are not hard once you understand how to read them. Keep it light and fun!

Practice questions

1. What do the points on a line graph show?
   Answer: They show the data values at specific times.
2. Which axis shows time?
   Answer: The horizontal axis (x-axis).
3. If a line graph goes up, what does it mean?
   Answer: The value is increasing over time.
4. If a line graph goes down, what does it mean?
   Answer: The value is decreasing over time.
5. How many points should you plot for 5 days of data?
   Answer: 5 points.

FAQ

What is a line graph used for?
Line graphs are used to show how data changes over time, like temperature, height, or money saved.

Can I use a line graph for any kind of data?
No, line graphs work best for data that changes over time and is continuous, like temperature or height.

Do I need to connect the points with lines?
Yes, connecting the points helps show the pattern of change over time.

What does a flat line mean?
A flat line means the value stays the same over time.

How do I read a line graph?
Look at the x-axis for time, the y-axis for values, and follow the line to see how the data changes.