Good Learning Co.
SavannahYear 8
← Maths
MathsStatistics24 min★★ difficulty

Scatter graphs and correlation

Plot height against shoe size for a class and a pattern usually appears — scatter graphs reveal relationships that a table of numbers hides.

Part of your national curriculum
  • Statistics: Describe simple mathematical relationships between two variables in observational and experimental contexts and illustrate using scatter graphs

Lesson overview

What you'll learn in this lesson

Describe simple mathematical relationships between two variables in observational and experimental contexts and illustrate using scatter graphs

Key learning points

  • • Types of correlation
  • • Worked example
  • • Reading a line of best fit

This lesson at a glance

  • 24 minutes
  • 13 parts to scroll through
  • 3 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

simplemathematicalrelationshipsvariablesobservational

Scroll down — the lesson carries on below

Part 1 of 13 · Discover8%
1

Watch & discover

Part 1 of 13

Watch first

Scatter graphs and correlation

An English teaching video on this topic from mathantics. Watch it, then scroll down for the lesson.

In a nutshell

Describe simple mathematical relationships between two variables in observational and experimental contexts and illustrate using scatter graphs

2

Learning cycle

Part 2 of 13

Learning cycle 1 of 2

Part 1 · Types of correlation

A short piece of teaching, then a check to make sure it has landed.

3

Explore the idea

Part 3 of 13

Learn

Types of correlation

Positive correlation: as one variable increases, so does the other (e.g. height and shoe size). Negative correlation: as one increases, the other decreases (e.g. car age and value). No correlation means no clear pattern.

4

Explore the idea

Part 4 of 13

Learn

Worked example

Given pairs (hours revised, test score): (1,40), (2,50), (3,65), (4,80). As hours increase, scores rise steadily — this is a positive correlation, and a line of best fit could estimate a score for 3.5 hours, around 72.

5

Quick check

Part 5 of 13

Quick check

Height and shoe size tend to increase together. What type of correlation is this?

6

Reset break

Part 6 of 13

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now
7

Quick check

Part 7 of 13

Quick check

A car's value tends to fall as its age increases. What type of correlation is this?

8

Learning cycle

Part 8 of 13

Learning cycle 2 of 2

Part 2 · Reading a line of best fit

A short piece of teaching, then a check to make sure it has landed.

9

Explore the idea

Part 9 of 13

Learn

Reading a line of best fit

A line of best fit is drawn through the middle of the scattered points, roughly balancing points above and below. It can be used to estimate values not directly measured, but only within a sensible range of the data.

10

Quick check

Part 10 of 13

Quick check

What is a line of best fit used for?

11

Challenge round

Part 11 of 13

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

12

Mastery quiz

Part 12 of 13

Marked quiz

End of lesson quiz: Scatter graphs and correlation

3 questions, marked with the reasoning shown. No timer.

  1. 1. Height and shoe size tend to increase together. What type of correlation is this?

  2. 2. A car's value tends to fall as its age increases. What type of correlation is this?

  3. 3. What is a line of best fit used for?

13

Lesson round-up

Part 13 of 13

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Article

The cost of a school trip

A school is planning a trip to a wildlife park. The coach costs £480 however many people go. Entry costs £9.50 for each pupil and each adult goes free. The school says every pupil must pay the same amount, and the trip must not lose money.

If 60 pupils go, the coach works out at £8 each, so the total for each pupil is £17.50. If only 40 pupils go, the coach works out at £12 each, so the price rises to £21.50. The teacher explains that the coach is a fixed cost and the entry is a cost per person — which is why the price per pupil changes when the number changes.

The school decides to charge £20 and to use anything left over for a second trip later in the year.

Written for Good Learning Co.

Reading questions

  1. Work out the total cost of the trip if 50 pupils go.
  2. Show why the price per pupil falls when more pupils go, using numbers.
  3. At £20 each, how many pupils must go before the trip makes money? Show your working.

  • Working out

    Working out

    Do the practice questions on paper, showing every step — not just the answer. Mark them yourself and circle anything you got wrong.

    10–15 questions

  • Worked example, explained

    Writing

    Copy one question out and write underneath, in words, why each step works.

    1 question, 4–5 sentences

  • Problem in words

    Working out

    Write your own real-life problem that uses today's method, then solve it.

    1 problem + solution

Saved as you type.

Part 1 of 13 · Watch & discover

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    Describe simple mathematical relationships between two variables in observational and experimental contexts and illustrate using scatter graphs

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