Free Grade 3 Polygons Flashcards
Free Grade 3 flashcards for Polygons: 12 real questions with a full answer key and worked solutions. Angles on a straight line add to 180°, around a point to 360°, and inside a triangle to 180°. A polygon with n sides has interior angles adding to (n − 2) × 180°.
Free
Stretch
30 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- RememberIdentify polygons
Identify polygons accurately in a familiar context.
Assessed by: Exit ticket of four short items
- UnderstandExplain polygons
Explain polygons accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate polygons
Calculate polygons accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare polygons
Compare polygons accurately in a familiar context.
Assessed by: Exit ticket of four short items
Prerequisites
Close these gaps first — each has its own free lesson, worksheet and quiz.
How Polygons works
Angles on a straight line add to 180°, around a point to 360°, and inside a triangle to 180°. A polygon with n sides has interior angles adding to (n − 2) × 180°.
12 practice questions
Easy to hard, 24 marks in total. Try them first, then open the answers.
- 1.Two angles on a straight line. One is 157°. Find the other.[1]
- 2.Two angles on a straight line. One is 72°. Find the other.[1]
- 3.Two angles on a straight line. One is 76°. Find the other.[1]
- 4.Two angles on a straight line. One is 67°. Find the other.[1]
- 5.A triangle has angles 38° and 113°. Find the third angle.[2]
- 6.A triangle has angles 51° and 64°. Find the third angle.[2]
- 7.A triangle has angles 20° and 33°. Find the third angle.[2]
- 8.A triangle has angles 86° and 67°. Find the third angle.[2]
- 9.Find the size of each interior angle of a regular 6-sided polygon.[3]
- 10.Find the size of each interior angle of a regular 8-sided polygon.[3]
- 11.Find the size of each interior angle of a regular 9-sided polygon.[3]
- 12.Find the size of each interior angle of a regular 7-sided polygon.[3]
Show answers and working
1. 23°
Angles on a straight line add to 180°. 180 − 157 = 23°.
2. 108°
Angles on a straight line add to 180°. 180 − 72 = 108°.
3. 104°
Angles on a straight line add to 180°. 180 − 76 = 104°.
4. 113°
Angles on a straight line add to 180°. 180 − 67 = 113°.
5. 29°
Angles in a triangle add to 180°. 180 − 38 − 113 = 29°.
6. 65°
Angles in a triangle add to 180°. 180 − 51 − 64 = 65°.
7. 127°
Angles in a triangle add to 180°. 180 − 20 − 33 = 127°.
8. 27°
Angles in a triangle add to 180°. 180 − 86 − 67 = 27°.
9. 120°
Sum of interior angles = (6 − 2) × 180 = 720°. Each angle = 720 ÷ 6 = 120°.
10. 135°
Sum of interior angles = (8 − 2) × 180 = 1080°. Each angle = 1080 ÷ 8 = 135°.
11. 140°
Sum of interior angles = (9 − 2) × 180 = 1260°. Each angle = 1260 ÷ 9 = 140°.
12. 128.57°
Sum of interior angles = (7 − 2) × 180 = 900°. Each angle = 900 ÷ 7 = 128.57°.
Worked examples
Two angles on a straight line. One is 95°. Find the other.
- Angles on a straight line add to 180°.
- 180 − 95 = 85°.
- Answer: 85°
A triangle has angles 33° and 77°. Find the third angle.
- Angles in a triangle add to 180°.
- 180 − 33 − 77 = 70°.
- Answer: 70°
Find the size of each interior angle of a regular 5-sided polygon.
- Sum of interior angles = (5 − 2) × 180 = 540°.
- Each angle = 540 ÷ 5 = 108°.
- Answer: 108°
Interactive practice
Free, no account required — answer on screen or print it.
Common mistakes
What learners typically get wrong, and how to fix it.
Reads the wrong scale on a protractor.
Correction: Start from the 0 on the arm you are measuring from.
Uses 360° for a triangle.
Correction: Triangle = 180°, quadrilateral = 360°.
Teacher tips
- · Estimate the angle type before measuring.
Parent tips
- · Spot right angles around the house.
Real-life applications
- · Ramps, clock hands, building and design.
Assessment objectives
How mastery is evidenced, and which standards it maps to.
Every free resource for Polygons
One concept, one ecosystem — all of it free.
Goes deeper
The entities below this one, each with the same complete free resource set.
Sibling concepts
Related concepts
Lateral links, including across subjects.
Next topics
All free formats for this concept
Every kind below is a real page, generated from this entity.
Learn — Meet the idea.
Practice — Build fluency.
Revise — Keep it in memory.
Assess — Prove mastery.
Apply — Use it in context.
Teach — Deliver it to a class.
Frequently asked
- Is this Grade 3 Polygons flashcards really free?
- Yes. Every flashcards on FreeMathWorksheet is free to use, print and share — no account, no paywall and no watermark.
- What should a learner already know before this?
- Start with Circles, Quadrilaterals, Angles. Each one has its own free lesson, worksheet and quiz.
- How is the flashcards sequenced?
- Recognition first, then understanding, application, reasoning and finally mastery — the same ladder used across every free resource on the platform.
- What comes next after Polygons?
- Move on to Symmetry, Angles, Perimeter and Area, 3D Shapes, which build directly on this idea.
Related resources
Stuck on Polygons? The AI Tutor already knows this page, its prerequisites and its common mistakes.
Open the free AI Tutor