Math // Number Representation & Place Value
Measuring temperature
Use negative numbers in context (temperature, finance, sea level); calculate intervals across zero
Quick check
If a bank account goes from −£45 to +£120, can the learner work out the total change — counting through zero to get £165?
Ask this to see whether the topic is secure.
Topic // Mastery
What mastery looks like
- The temperature falls from 3°C to −5°C — what is the drop? (8 degrees)
- Calculate the difference between a bank balance of −£120 and £350
- Order −7, −3, 0, 2, 5 on a number line and find the interval from −7 to 5
Topic // Map
Where this fits
- RequiredMust come first
- HelpfulHelps, but not essential
Before this
1 topic- Negative numbers in contextRequired
Number Representation & Place Value // Ages 9 to 10
Calculating intervals across zero extends Y5 negative number context
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Measuring temperature
Ages 10 to 11 // Method
Leads to
5 topics- Coordinates (age 10+)Required
Geometry // Ages 10 to 11
Negative coordinates require understanding of negative numbers
Number Representation & Place Value // Ages 11 to 12
Ordering with inequality symbols extends Y6 work with negative numbers in context
- Positive and Negative NumbersRequired
Addition & Subtraction // Ages 11 to 13
Negative number arithmetic extends Y6 using negative numbers in context
- Linear number sequencesHelpful
Algebra // Ages 10 to 11
Sequences crossing zero require negative number understanding
- Numbers to Ten MillionHelpful
Number Representation & Place Value // Ages 10 to 11
Negative number problems may appear in context
Topic // Research-informed
Teaching notes
From the Marble Skill Taxonomy. These notes have not been validated in classrooms, so treat them as a starting point for your own judgement.
The approach
For ages 10–11: use negative numbers in directed real-world contexts (temperature, bank balance, sea level) and calculate intervals across zero as a distance on the number line. The key insight is that an across-zero interval decomposes at zero into two magnitudes that ADD (e.g. −2 to 3 = 2 + 3 = 5), and that ordering depends on direction, not digit size (−5 sits below −3 even though 5 > 3). Signed +/−/× arithmetic rules are deferred to later study.
Common misconceptions
- Treating −5 as larger than −3 because '5 > 3' (ignoring direction)
- Counting the interval across zero without including the step onto/over 0, or double-counting zero
- Adding the numbers instead of finding a distance (−5 to 3 answered as −2)
- Believing there is no number between −1 and 1 other than described, or that zero is negative/positive
- Reading a fall in temperature as a rise because the digit gets 'bigger' (−2 to −8 seen as warming)
Useful representations
- Vertical number line / thermometer spanning below and above zero
- Horizontal number line with zero as the crossing point and interval arcs
- Real-context strips: temperature scale, sea-level cross-section, bank balance line
- Interval arcs decomposed at zero (−5→0 is 5, 0→3 is 3, total 8)
Teaching practices
- Anchor every negative in a directed context (temperature, sea level, bank balance) so the sign means a direction, not a smaller ordinary number
- Compute intervals across zero as a distance on the number line — count/measure through zero, or add the two sides' magnitudes
- Use a VERTICAL number line (thermometer) for temperature/sea level so 'colder/lower' maps to physically down
- Keep the focus on ordering and intervals; defer signed +/−/× arithmetic rules to KS3
- Contrast 'the difference between −5 and 3' (interval = 8) with the values themselves, so distance is not confused with a single number's value
Activities to try
- 1
Dragging across zero on a vertical number line (thermometer)
Why it works: An interval that spans zero is the sum of the two distances on each side of zero; direction (not the size of the digit) sets the order of negative numbers, so −5 lies below −3.
- Set a start value (e.g. −2°C) and an end value (e.g. 3°C) on a vertical number line scaled like a thermometer.
- Drag a marker from the start up through zero to the end, watching the interval light up as two arcs meeting at zero: '2 below → 0' and '0 → 3'.
- Read the running interval as it decomposes: 2 + 3 = 5, rather than a single subtraction.
- Switch the context (temperature → sea-level cross-section → bank balance, e.g. −£120 below zero and £350 above) while the same number line stays, and repeat the drag.
- Compare the positions of −5 and −3 on the scale and state which is lower and why.
- 2
Explain-the-error dialogue: 'convince me on the line'
Why it works: Verbalising why the zero crossing must be counted exposes the 'subtract the magnitudes' error and reinforces that the interval is the sum of both sides.
- Consider a claim such as: 'The temperature fell from 3°C to −5°C, so it dropped 2 degrees.'
- Decide whether it is right or wrong, and use a number line to justify your answer.
- State where zero is in the journey and how far you travel on each side of it.
- Explain in words why the answer is not simply 5 − 3 = 2.
- 3
Ordering and interval consolidation
Why it works: Ordering negatives and computing across-zero intervals become reliable once the number-line intuition is applied consistently across contexts.
- Order a set such as −7, −3, 0, 2, 5 from lowest to highest and place them on a number line.
- Find the interval from −7 to 5 by splitting at zero: 7 (below) + 5 (above) = 12.
- Set a temperature after a stated fall (e.g. start 3°C, fall 8 degrees → −5°C) by marking it on the line.
- Find the difference between a balance of −£120 and £350 and check it against the 'add both sides' method: 120 + 350 = 470.
Topic // Standards
Curriculum standards
- The national curriculum in England: Key stages 1 and 2 framework document
- Ma6/2.1c
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