Reach for the Star

Triangles and polygons · Optional extension

L026 · Allow 10–15 minutes for learners ready to move on. Answers are available after an attempt.

Stretch

Find each interior angle of a regular 15-sided polygon.

Reveal a worked check after attempting

Exterior angle=360/15=24°, interior=156°.

Deep challenge

A regular polygon has interior angle 165°. Find its number of sides.

Reveal a worked check after attempting

Exterior=15°, sides=360/15=24.

Recall & Review: feedback and extension integration

Lesson L026: Triangles and polygons

Objective: Derive angle sums and use triangle, quadrilateral and regular-polygon properties to solve problems.

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: Find each interior angle of a regular 15-sided polygon.

Deep challenge: A regular polygon has interior angle 165°. Find its number of sides.