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scatter graph
Each point preserves a time/position pair.
Class 8 · English Medium · Pearson Edexcel · General science
Pearson Lower Secondary Science qualification specification, Issue 2 November 2024 · Chapter companion part
Year 8 · Recording evidence and choosing graphs
Build Year 8 enquiry skills: recording evidence and choosing graphs, using supplied data and your own reasoning.
Original Year 8 practice for shared Pearson Year 7–9 scientific enquiry objectives. The Class 8 Edexcel course slot provides access; confirm programme-year placement with a teacher. This is selected companion practice, not full national, Cambridge or Pearson programme coverage.
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Learn the idea
Record observations when they are supplied or made; distinguish original readings from calculated results and estimates. Include quantities, units and conditions. A labelled scientific diagram describes relevant features with clear lines; it is not decorative art or proof that an unseen feature was observed.
Tables and graph conventions
A table needs meaningful column headings, with units such as time / s or length / cm. Put the independent quantity on the horizontal axis in these examples and the dependent quantity on the vertical axis. Use even numerical spacing and label both axes. Select a scale that shows the data clearly rather than exaggerating a difference.
Choose a graph for the data
A bar graph compares categories, with separate bars. A scatter graph shows paired numerical measurements as points. A line graph can show how a quantity changes in a meaningful sequence, such as time. The choice should follow the question and data, not a rule that every set of numbers needs a line through every point.
A trend line is a model
A line of best fit represents the overall pattern in suitable scattered numerical data. For an approximately straight pattern, place a reasonable line through the trend with points roughly balanced on either side. It need not pass through every point or the origin. Read between measured inputs cautiously; a prediction beyond them needs extra caution.
Use a less-perfect numerical pattern
A supplied virtual trolley record pairs times 0, 1, 2 and 3 s with positions 2, 4, 9 and 11 cm. The points show an increasing pattern with scatter around an approximately straight trend. Position begins at 2 cm in the model coordinate system, so an origin-passing line should not be imposed without evidence.
Read the stated trend model
For this task the supplied approximate trend line is position = 2 + 3 × time. At 1.5 s it estimates 6.5 cm. The line is not a claim that the observed 4 cm point at 1 s must be changed to 5 cm. Keep original points and the fitted model separate; a reasonable manual line need not be an exact mathematical optimum.
Choose scales without distortion
The graph includes both zero and the non-zero starting position, clearly labelled seconds and centimetres, and even numerical intervals. A shortened axis can be used in some contexts only when clearly indicated, but it can exaggerate apparent differences. A companion table preserves exact supplied values and makes the picture accessible.
Distinguish categories, sequences and curves
Separate bars compare cloth categories A, B and C. Scatter points show paired numerical readings. A cooling time series may curve rather than follow one straight trend; joining an ordered sequence or describing its curve can suit the question better. A scientific diagram should state which features were supplied rather than filling in imagined observations.
Worked example
The supplied approximate line 2 + 3 × time gives 9.5 cm at 2.5 s. The observed points remain (0,2), (1,4), (2,9), (3,11). The 1 s point lies below this line and the 2 s point above it; the line describes a trend rather than replacing the readings.
- Identify the question, variables and supplied evidence.
- Show calculations with units and distinguish readings from estimates.
- Explain the conclusion, then name a limitation and a useful next step.
Common mistake
A trend line estimates a pattern; it is neither an extra observation nor a reason to change a scattered point.
A non-zero start
Position 2 cm at time zero belongs on the graph. A forced zero intercept would change the supplied model.
A curve check
Drops of 10,7,5 °C in equal time intervals are not equal; a constant-rate line would conceal that changing pattern.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
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bar graph
The names are categories, not numerical intervals.
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interpolation
Interpolation uses a model within the range of given inputs.
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extrapolation
Extrapolation needs caution because the pattern may change beyond the supplied data.
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time
The horizontal scale is time in seconds.
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6.5
2 + 3 × 1.5 = 6.5 cm, an estimate rather than a new observation.
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9.5
2 + 3 × 2.5 = 9.5 cm within the supplied time range.
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9
The vertical position coordinate is 9 cm.
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1
5 − 4 = 1 cm below the model line; keep the original point.
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2
12 ÷ 6 = 2 cm per equal interval.
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Use time / s and position / cm; the coordinate system can start the trolley at 2 cm, so the first supplied point is (0,2).
Preserve quantities, units and the actual starting position.
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The observed point and the model estimate are different records; altering the reading would hide the scatter and misrepresent evidence.
The model describes evidence; it does not rewrite it.
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At 1 s the point is 1 cm below the line; at 2 s the 9 cm point is 1 cm above the line’s 8 cm estimate.
Use values and directions, and recognise this is a supplied approximate model.
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The spacing represents equal changes; inconsistent spacing distorts the relationship shown.
Connect the scale convention to meaning rather than appearance alone.
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The decreases are 10, 7 and 5 °C over equal times, so the rate of decrease changes and a curve may describe the pattern better.
Compare equal time intervals and keep the values as supplied model data.
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State that it represents the supplied image or model, label relevant visible features, and avoid claiming unseen structures were observed.
Keep the source and limits of the representation visible.
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2.5 s lies between supplied inputs; 20 s is outside the 0–3 s range and assumes the model continues much farther.
Define interpolation and extrapolation in plain words.
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An undisclosed break changes the apparent size of differences; labels and a clear break are needed to show the actual scale.
A graph choice should communicate, not exaggerate, the evidence.
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List the labelled time/position pairs in a table and use labels or shapes as well as colour.
The exact data should remain obtainable without colour recognition.
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A zigzag can suggest a sequence or exact path that the paired observations do not establish; an appropriate trend representation answers the stated question better.
Choose the representation from the data meaning and scientific question.
Enquiry notebook challenge
Plot the supplied trolley points and line, and explain the cooling graph choice. Then use an independent paper dataset: (1 s,3 cm), (2 s,6 cm), (3 s,7 cm), (4 s,10 cm). Draw your own reasonable trend line and estimate position at 2.5 s. State its limits.
Review with a guardian or teacher
- Preserve paired observations, labels and units.
- Distinguish approximate models from readings and justify the cooling representation.
- For the independent data, justify a reasonable fit rather than joining every point. One review example, position ≈ 1.5 + 2 × time, estimates 6.5 cm at 2.5 s; other supported hand-drawn fits can be valid.
Keep your work on paper or in a local file. This page does not upload it or automatically grade the project.
Curriculum companion and further study
This original Kidemy practice is mapped to selected Year 8 objectives in the Pearson Lower Secondary Science qualification specification, Issue 2 November 2024, PDF page 45. This public source does not establish the full programme or a complete textbook chapter list.
Pearson qualification specification and source →
Continue with your teacher and programme materials
- Apply the enquiry skills to further biology, chemistry and physics contexts with a teacher.
- Independent practical assessment and the wider programme objectives remain; supplied model data do not establish hands-on competence.
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