Signed numbers · Optional extension
L001 · Allow 10–15 minutes for learners ready to move on. Answers are available after an attempt.
Stretch
Calculate −18+27−35 and check by grouping in a second way.
Reveal a worked check after attempting
−26; for example (−18+27)−35=9−35=−26.
Deep challenge
A learner claims subtracting a negative always gives a positive answer. Test the claim with a counterexample.
Reveal a worked check after attempting
False: −8−(−3)=−5, still negative.