L004 · Allow 10–15 minutes for learners ready to move on. Answers are available after an attempt.
A learner calculates −7−(−12)=−19. Locate the first error and repair it.
Subtracting −12 means add 12, so −7+12=5.
Create an independent check for 35×0.8=28 that does not simply repeat the multiplication.
0.8=4/5, and 35÷5×4=28; or 80% of 35=28.
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.
I used my working and assessment evidence to identify the exact mathematical step that was secure and the specific misconception that needs attention.
I will correct one precise step, explain why the correction works and complete a fresh delayed question without the original scaffold.
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.