Q4, W1: March 21-25 Geometry

TeacherKristin Andreason
Subject AreaGeometry Honors
Grade Level8
Week #March 21-25
Unit of InstructionUnit 6: Two-Dimensional Measurements
Standard(s) Taught

MAFS.912.G-GMD.1.1:  Give an informal argument for the formulas for the circumference of a circle, area of a circle, volume of a cylinder, pyramid, and cone. (Use dissection arguments, Cavalieri’s principle, and informal limit arguments.)

MAFS.912.G-CO.4.13:  Construct an equilateral triangle, a square, and a regular hexagon inscribed in a circle.

MAFS.912.G-CO.1.3:  Given a rectangle, parallelogram, trapezoid, or regular polygon, describe the rotations and reflections that carry it onto itself.


Learning Targets and Learning Criteria
  • define regular polygons.
  • inscribe a regular polygon in a circle and break it into many congruent triangles to find its area.
  • explain and use the dissection method on regular polygons to generate an area formula for regular polygons A = ½ × apothem × perimeter (A = aP).
  • calculate the area of a regular polygon A = ½ × apothem × perimeter   (A = ½aP).
  • use pictures to explain that a regular polygon with many sides is nearly a circle, its perimeter is nearly the circumference of a circle, and that its apothem is nearly the radius of a circle.
  • substitute the “nearly” values of a many sided regular polygon into   A = ½ × apothem × perimeter (A = ½aP) to show that the formula for the area of a circle is A = LaTeX: \piπr2.
  • construct an equilateral triangle, a square, a hexagon inscribed in a circle.
  • explain the steps to constructing an equilateral triangle, a square, and a regular hexagon inscribed in a circle.
  • calculate the number of lines of reflection symmetry and the degree of rotational symmetry of any regular polygon.
  • predict and verify the sequence of transformations (a composition) that will map a figure onto another.
Classroom Activities


  1. We will watch a video showing how we get the formula for area of a circle.
  2. I will give students notes on Regular Polygons.
  3. Students will create a foldable on Area of Regular Polygons with practice examples.
  4. Students will begin a Scavenger Hunt on the Area of Regular Polygons


  1. Students will take notes on Density and Population Density
  2. Do IXL W.10 together
  3. We will look at how to inscribe a square, equilateral triangle, and hexagon in a circle


  1. Students will take notes on Rotational Symmetry
  2. We will do IXL L.12 together
  3. We will also talk about Line Symmetry and do IXL O.1
  4. We will talk about transformations that carry a figure onto another
  5. We will do a practice sheet and maybe IXL L.11
Assignments Due
  • Scavenger hunt on Area of Regular Polygons.
  • Area of compound figures (started before break)
  • Area and perimeter on coordinate plane (started before break)
Additional Resources

All IEP and ESOL accommodations are provided daily.