Reach for the Star

Number diagnostic and repair

Pearson Edexcel GCSE Mathematics 1MA1 · Foundation and Higher · L004 · Review v0.9

Your learning journey

Diagnose a number error, repair the method, and choose an independent check that tests the original calculation.

Work without a calculator except for an invited check. Keyboard - means the same as −. Attempt before opening a scaffold or intentional practice explanation.

Answers save in this browser where storage is permitted. They do not sync. Export a backup before closing, moving or renaming this file. Avoid personal information.

Ready.

Connect & Check

Diagnostic: evidence used to choose what to reteach. Inverse: an operation that undoes another. Estimate: an approximate check of size. Counterexample: one case disproving an always claim. Evidence: working that supports a conclusion.

Intentional practice feedback after your attempt

−2; 12. Example check: −2 + (−5) = −7.

Record the first error before checking feedback.

Intentional practice feedback after your attempt

12; 1. First divide 18 by 3; first multiply 3 by −2.

Equal-priority operations go left to right.

Intentional practice feedback after your attempt

48; 6.29.

Keep the place-value and rounding decisions visible.

Wider prerequisite screen — ungraded

Plan support for later units. This is not a test of this week’s taught content or an entry-tier decision. Your teacher reviews the responses.

Share

In pairs, predict the first step and compare your reasons before reading the worked solution: D1 A learner writes −6 − (−4) = −10. Repair: subtracting −4 adds 4, so −2. Check −2 + (−4) = −6. Now repair −8 − (−3) = −11.

Present

A correct answer copied from feedback does not establish secure understanding. Use attempt → locate the first error → explain and repair → check independently → solve a fresh matched problem after a delay. Match the check to the risk: inverse for an operation, place value for scale, estimate for magnitude, and substitution into the original expression for a missing number.

Keep the original calculation visible. Repeating the same incorrect method is not an independent check. A useful repair names the decision that went wrong and succeeds on a fresh question with the support removed.

Optional scaffold

Rewrite as adding the opposite.

Intentional practice feedback after your attempt

−5; inverse check −5 + (−3) = −8.

The original error treats subtraction as adding the same signed number.

Optional scaffold

Circle multiplication before doing any addition.

Intentional practice feedback after your attempt

−8; 1.

The first error was adding 6 and 2 before multiplying.

Optional scaffold

Compare the result with the starting value.

Intentional practice feedback after your attempt

The number was made ten times smaller instead of one hundred times larger. Correct original: 36. Fresh answer: 72.

Track each digit’s place value.

Optional scaffold

Distinguish reasonable from exact.

Intentional practice feedback after your attempt

No. It supports the scale; an exact calculation or inverse check is still needed.

Different nearby values can all be reasonable.

Apply

Intentional practice feedback after your attempt

−3, checked by −3 + (−6) = −9; 4, checked by (−8) × 4 = −32.

Use the original signed number in the inverse check.

Intentional practice feedback after your attempt

18; −7. First steps 24 ÷ 4 = 6 and 2 × (−6) = −12.

Remove the operation-order prompt once the first step is secure.

Optional scaffold

Name the purpose of each method.

Intentional practice feedback after your attempt

84; 7.39; 80.

Track value, mark the decision digit, then estimate separately.

Core work is non-calculator. After A3, a calculator may confirm 19.7 × 4.2 = 82.74. Estimate first: 20 × 4 = 80. A display can confirm arithmetic, but does not explain an error or prove understanding.

Apply and extend

Intentional practice feedback after your attempt

No. Repeating 2 + 3 × 4 as (2 + 3) × 4 gives 20 twice; the correct value is 14.

A repeated misconception can reproduce the same error.

Optional scaffold

Split 4.2 into 4 + 0.2.

Intentional practice feedback after your attempt

Use exact calculation: 19.7 × 4 = 78.8 and 19.7 × 0.2 = 3.94; sum 82.74.

Estimation cannot distinguish every pair of nearby answers.

Access, Scaffold, Core and Stretch support the same goal. Stretch deepens reasoning for either qualification tier.

Recall & Review

Retrieval without notes

Six retrieval points. Enter a number, decimal, fraction such as 3/2, or mixed number such as 1 1/2. Equivalent numeric values are accepted. Unsupported notation goes to teacher review. For rounding, also communicate the requested accuracy in written work; numerical scoring cannot judge significant trailing zeros.







Not checked.

Independent exit evidence

P1–P2: five minutes, no notes, 4 marks. Your teacher reviews working and explanations. Full assessment solutions are not embedded.

Recall & Review and prepare

A factor divides a whole number exactly. The positive factors of 12 are 1, 2, 3, 4, 6 and 12. A prime is an integer greater than 1 with exactly two positive factors. Pair factors systematically to avoid missing one.

Retrieve F1 again in one week. Bring your working and one question.

Your progress summary

Completion records attempts, not mastery. Retrieval points describe the latest checked attempt. Your teacher reviews P1–P2 separately and checks retained understanding after a delay.

Restore a backup

Original Reach for the Star. Not an official or endorsed Pearson resource. Separate teacher package contains assessment solutions. Local saving is browser-dependent; no account or dashboard service is included.

Optional extension activities

Stretch

Check after attempting

Subtracting −12 means add 12, so −7+12=5.

Deep challenge

Check after attempting

0.8=4/5, and 35÷5×4=28; or 80% of 35=28.

Recall & Review: feedback and extension integration

Lesson L004: Number diagnostic and repair

Objective: Diagnose a number error, repair the method, and choose an independent check that tests the original calculation.

60-minute structure: 0-7 Connect & Check; 7-14 Share; 14-25 Present/model; 25-44 Apply route choice/practice; 44-52 independent exam-style check; 52-60 Recall & Review, WWW/EBI and next step.

What Went Well (WWW)

I used my working and assessment evidence to identify the exact mathematical step that was secure and the specific misconception that needs attention.

Even Better If (EBI)

I will correct one precise step, explain why the correction works and complete a fresh delayed question without the original scaffold.

Stretch and deep challenge

Stretch: A learner calculates −7−(−12)=−19. Locate the first error and repair it.

Deep challenge: Create an independent check for 35×0.8=28 that does not simply repeat the multiplication.