📊 Statistics District · Scatter graphs
Use plotted paired data to interpret line of best fit with careful statistical language. In this lesson, focus on a scatter graph shows whether two variables tend to change together.
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Use plotted paired data to interpret line of best fit with careful statistical language. In this lesson, focus on a scatter graph shows whether two variables tend to change together.
A scatter graph shows whether two variables tend to change together. A line of best fit should pass through the middle of the cloud with a balanced spread of points, while an outlier needs separate attention. For line of best fit, the final written answer should make that exact relationship visible rather than hiding it inside an unexplained result.
Line of best fit: A scatter graph shows whether two variables tend to change together. Check that a best-fit line leaves a sensible balance of points above and below it. Keep the line of best fit representation visible until the final line.
Plot paired points, drag a line through the data cloud and compare balanced and biased fits. Use the model to explain one change you notice while working on line of best fit.
Check that a best-fit line leaves a sensible balance of points above and below it. Write that check beside the final line of best fit answer.
Given information: Line of best fit — A scatter graph for study time and test score has points that rise from left to right. Identify the correlation. Method choice: Substitute the x-coordinate into the equation. Compare the calculated y-value with the point's y-coordinate. Calculation or reasoning: The points rise from left to right: as study time increases, test score tends to increase. This overall upward trend is positive correlation. Final answer: positive correlation. Check: Compare the calculated y-value with the point's y-coordinate.
Visual / interactive
Plot paired points, drag a line through the data cloud and compare balanced and biased fits. Use the model to explain one change you notice while working on line of best fit.
Worked examples
Understand the idea with small numbers, one representation and one clear step.
Use the standard Year 8 method with mixed examples and normal wording.
Handle multi-step or less familiar questions and explain choices.
Solve a worded question, show reasoning, check accuracy and write a final sentence.
Given information: Line of best fit — A scatter graph for study time and test score has points that rise from left to right. Identify the correlation. Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: A scatter graph for study time and test score has points that rise from left to right. Identify the correlation. Final answer: positive correlation. Check: substitute or compare with the original information to confirm the result fits the question.
Given information: Line of best fit — The points for temperature and coat sales cluster closely around a downward-sloping line. Describe the relationship fully. Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: The points fall from left to right and stay close to a line, so the graph shows strong negative correlation. Final answer: strong negative correlation. Check: substitute or compare with the original information to confirm the result fits the question.
Check: Check the line of best fit result against the original information.
Given information: Line of best fit — Most plotted points are near (2, 5), (3, 7), (4, 9), (5, 11), but one point is (9, 2). Which coordinate is the outlier? Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: (9, 2) is far away from the overall upward pattern, so it is the outlier. Final answer: (9, 2). Check: substitute or compare with the original information to confirm the result fits the question.
Try explaining why each step works before checking the answer.
Given information: Line of best fit — A line of best fit is modelled by y = 4x + 6. Estimate y when x = 4. Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: Substitute x = 4: y = 4 × 4 + 6 = 22. Final answer: 22. Check: substitute or compare with the original information to confirm the result fits the question.
Check that a best-fit line leaves a sensible balance of points above and below it. Write that check beside the final line of best fit answer.
Create a line of best fit problem with a tempting incorrect answer. Solve it, apply the check, and explain exactly where the incorrect method breaks down.
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Use trend line controls to solve three checked line of best fit rounds. Solve at least two of three marked rounds and use feedback to correct any error.
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Line of best fit: A scatter graph shows whether two variables tend to change together. Check that a best-fit line leaves a sensible balance of points above and below it. Keep the line of best fit representation visible until the final line.
Tap to mark reviewedpaired data · correlation · outlier · line of best fit · interpolation · line · best
Tap to mark reviewedRead both variable axes and plot paired points. Describe direction and strength without claiming causation. Notice any outlier. For a line of best fit, balance points above and below before estimating. Record the check explicitly for line of best fit.
Tap to mark reviewedGiven information: Line of best fit — A scatter graph for study time and test score has points that rise from left to right. Identify the correlation. Method choice: Substitute the x-coordinate into the equation. Compare the calculated y-value with the point's y-coordinate. Calculation or reasoning: The points rise from left to right: as study time increases, test score tends to increase. This overall upward trend is positive correlation. Final answer: positive correlation. Check: Compare the calculated y-value with the point's y-coordinate.
Tap to mark reviewedGiven information: Line of best fit — A scatter graph for study time and test score has points that rise from left to right. Identify the correlation. Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: A scatter graph for study time and test score has points that rise from left to right. Identify the correlation. Final answer: positive correlation. Check: substitute or compare with the original information to confirm the result fits the question.
Tap to mark reviewedGiven information: Line of best fit — The points for temperature and coat sales cluster closely around a downward-sloping line. Describe the relationship fully. Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: The points fall from left to right and stay close to a line, so the graph shows strong negative correlation. Final answer: strong negative correlation. Check: substitute or compare with the original information to confirm the result fits the question.
Tap to mark reviewedGiven information: Line of best fit — Most plotted points are near (2, 5), (3, 7), (4, 9), (5, 11), but one point is (9, 2). Which coordinate is the outlier? Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: (9, 2) is far away from the overall upward pattern, so it is the outlier. Final answer: (9, 2). Check: substitute or compare with the original information to confirm the result fits the question.
Tap to mark reviewedGiven information: Line of best fit — A line of best fit is modelled by y = 4x + 6. Estimate y when x = 4. Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: Substitute x = 4: y = 4 × 4 + 6 = 22. Final answer: 22. Check: substitute or compare with the original information to confirm the result fits the question.
Tap to mark reviewedClaiming correlation proves causation. This is a key trap when answering line of best fit questions.
Tap to mark reviewedFor line of best fit, show the key representation before the final calculation. Use this final check: Check that a best-fit line leaves a sensible balance of points above and below it.
Tap to mark reviewedScientific investigations, Comparing trends
Tap to mark reviewedI can explain line of best fit, use the method, check for mistakes, and answer an exam-style question.
Tap to mark reviewedI’m Stuck
Use this whenever a question feels confusing. Nothing here is locked.
Line of best fit: A scatter graph shows whether two variables tend to change together. Check that a best-fit line leaves a sensible balance of points above and below it. Keep the line of best fit representation visible until the final line.
Think of line of best fit as a careful model: make the important values visible, change one thing at a time, and use the check to prove the answer fits.
Start by naming the given information and the exact result required for line of best fit.
Read both variable axes and plot paired points.
Given information: Line of best fit — A scatter graph for study time and test score has points that rise from left to right. Identify the correlation. Method choice: use the line of best fit method and show each step with the stated values. Calculation or reasoning: A scatter graph for study time and test score has points that rise from left to right. Identify the correlation. Final answer: positive correlation. Check: substitute or compare with the original information to confirm the result fits the question.
Method: Read both variable axes and plot paired points. → Describe direction and strength without claiming causation. → Notice any outlier. → For a line of best fit, balance points above and below before estimating. Record the check explicitly for line of best fit.
Claiming correlation proves causation. This is a key trap when answering line of best fit questions.
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