L017 · Allow 10–15 minutes for learners ready to move on. Answers are available after an attempt.
If a=−2 and b=5, evaluate 3a²−2b and 2(a+b).
12−10=2; 2×3=6.
A learner interprets 3x² as (3x)². Use x=2 to expose the error.
3x²=12 while (3x)²=36.
Lesson L017: Algebraic language and substitution
Objective: Read algebraic notation accurately. Substitute signed values and distinguish expressions, equations and identities.
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 wrote the algebraic structure accurately and used a valid step-by-step method.
I will show inverse operations clearly, keep signs/brackets accurate and substitute back to check.
Stretch: If a=−2 and b=5, evaluate 3a²−2b and 2(a+b).
Deep challenge: A learner interprets 3x² as (3x)². Use x=2 to expose the error.