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PlayOwl

Mathematics · Grade 7

Circles, Angles and Area

Learners discover π as the constant ratio of circumference to diameter, use C = πd and A = πr² with exact answers in terms of π and approximations with π ≈ 3.14, and see why the area formula works by rearranging wedges. They then write and solve equations for unknown angles using complementary, supplementary, vertical and adjacent angles, and find areas of composite figures made of polygons and parts of circles.

  • 4 lessons
  • About 95 minutes
  • Circles, angles and area check: 11 questions
  • Ways to answer: fill in the blanks, choose an answer, match pairs, type a number, place on a number line and sort into groups
See plans Included with Family, Teacher and School plans. Open in PlayOwl

What learners will discover

  • Explain that π is the ratio of circumference to diameter and use C = πd = 2πr to find a circumference, or a diameter or radius from a circumference.
  • Use A = πr² to find the area of a circle exactly (in terms of π) or approximately, and explain the formula informally by rearranging the circle into a near-parallelogram.
  • Use complementary, supplementary, vertical and adjacent angle relationships to write and solve equations for unknown angles.
  • Find the area of composite figures made of rectangles, triangles and parts of circles by adding or subtracting areas.

Lessons

  1. Circumference and the number π 9 steps5 practiceabout 23 min
  2. The area of a circle 9 steps6 practiceabout 24 min
  3. Angle relationships and equations 9 steps5 practiceabout 22 min
  4. Area of composite figures 9 steps5 practiceabout 26 min
  5. Circles, angles and area check 11 questions at the end

Keep exploring

Games to practice with

  • Number-Line HopHelp the frog hop to the right number — from counting to negative fractions.
  • Ratio KitchenScale recipes, fill ratio tables and find the better buy.
  • Coordinate CourierDrive the parcel van to the right address on the coordinate grid.

More 7th grade math

Guide for grown-ups