Reach for the Star

Perimeter and compound area · Optional extension

L033 · Allow 10–15 minutes for learners ready to move on. Answers are available after an attempt.

Stretch

A rectangle 12 cm by 8 cm has a 3 cm by 2 cm corner cut out. Find area and perimeter.

Reveal a worked check after attempting

Area=96−6=90 cm²; perimeter remains 40 cm for a corner notch.

Deep challenge

Two shapes each have area 36 cm². Must their perimeters be equal? Give a counterexample.

Reveal a worked check after attempting

No. A 6×6 square has perimeter 24 cm; a 4×9 rectangle has perimeter 26 cm.

Recall & Review: feedback and extension integration

Lesson L033: Perimeter and compound area

Objective: Calculate perimeters and areas of compound rectilinear shapes, triangles, parallelograms and trapezia with correct units.

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 selected the correct geometric fact, theorem, formula or transformation and used a clear diagram with appropriate labels and units.

Even Better If (EBI)

I will name the fact or theorem, show the substitution or construction step and check whether the size, direction and units of the result are reasonable.

Stretch and deep challenge

Stretch: A rectangle 12 cm by 8 cm has a 3 cm by 2 cm corner cut out. Find area and perimeter.

Deep challenge: Two shapes each have area 36 cm². Must their perimeters be equal? Give a counterexample.