Geometry Lesson
The Perfect Slice: Circle Geometry at the Pizza Parlor
Shared by A STEM Educator
High School3-act-mathCCSS.MATH.CONTENT.HSG.C.A.2, CCSS.MATH.CONTENT.HSG.C.A.5, CCSS.MATH.CONTENT.HSG.GMD.A.150 min
Learning Objective
Students will apply relationships among central angles, inscribed angles, intercepted arcs, and sector area formulas to solve multi-step problems in real and abstract contexts.
Lesson Overview
Students use a viral pizza-cutting dispute to explore central angles, inscribed angles, arc measures, and sector area. The lesson builds from estimation to precise calculation using the full circle geometry toolkit.
Materials
- Printed or projected lesson slides
- Rulers and protractors
- Colored pencils (for arc/sector shading)
- Scientific or graphing calculators
- Whiteboards or large paper for group work
- Exit slip handout
Scaffolded Task Progression
1Task 1
Look at the pizza image. List THREE things you notice and TWO things you wonder. Then make an estimate: what is the central angle of the largest slice? The smallest? Record a 'too low,' 'too high,' and 'best guess' for each.
2Task 2
Before any measurements are given: what information would you NEED to find the exact area of each slice? Make a list. Then sketch a circle and label what a 'central angle' and an 'arc' are on your sketch.
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