Area of a sector
- Twice the size, twice the price? — 3 tasks
- Twelve equal panes — 3 tasks
- One fraction, two wholes — 3 tasks
- Double the radius — 3 tasks
- Going Deeper — 5 tasks
- Practice — 27 tasks
- Summary — 2 tasks
- Cool-down — 3 tasks
Classroom activities
Things a class does rather than writes on. Each one is a finished PDF: print it, cut it up if it says so, and hand it round.
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Same Area? Sectors That Look Alike. Area of a Sector — Cut & Glue Sort 25 minutes, including the cutting · 5 sheets
12 pieces, each two sectors described in words: an angle and a radius or a diameter, an area or an arc length, or no radius at all. Students sort each pair: same area, different areas, or cannot tell. Equal arcs do not mean equal areas, and different angles can give the same area.
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Area of a Sector: What Fraction of the Circle? Sector Area to the Nearest Unit — Answer Maze 10–15 minutes · 4 sheets
8 boxes on one page, each a circle with a sector filled with slanted lines and its angle marked at the center. The words give the radius or the diameter. Students find the sector's area to the nearest whole square centimeter. The wrong answers are the two commonest mistakes: using the diameter as the radius, and finding the arc length instead of the area. The row of box numbers at the foot is the check.
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Area or Length? Sector Area and Arc Length — Mystery Picture 25–35 minutes · 5 sheets
25 squares, each a circle with a sector filled with slanted lines and one line of someone's working. Every working is right, but some find the area of the sector and some find the length of its arc. Students decide one thing: does the working find the area? An area multiplies a length by a length. Fill it or leave it white, and a picture appears.
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Area of a Sector: What Fraction of the Circle? Sector Area in Terms of π — Scavenger Hunt a full class period · 13 sheets
16 cards around the room, each a circle with a sector filled with slanted lines and the angle at the center marked. The words give the radius or the diameter, and sometimes the marked angle belongs to the other sector. Students find the sector's area as a fraction of πr², in terms of π. Using the diameter as the radius, or the other sector's angle, lands on a card that sends the group back, and a clean run is 8 lines on the record sheet.