Year 2 Lesson Plan 6 - Areas of Composite Figures

  1. (5 min) Mental Math
    1. What is 4 times 6 divided by 2? [12]
    2. What is 75% of 200? [150]
    3. What is the perimeter of a pentagon whose sides are 3 in? [15 in]
    4. What is the perimeter of an equilateral triangle whose sides are 4 in? [12 in.]
    5. Take the number of sides in a hexagon, multiply by 10, then divide by 2 [30]
  2. (5 min) Review selected problems from lesson 5 (no more than 3 problems)

  3. (5 min) Review areas of polygons:
    • Pass out the "areas of polygons" handout.
    • Discuss the areas of various polygons
    • Draw this trapezoid on the board and have the students help you compute the area of this trapezoid:

      Use the trapezoid formula: (b1 + b2) h / 2 and
      also solve by cutting into two triangles. Draw the diagonal and ask students to compute the areas of the 2 triangles and add. They should add to the same value as the formula.
  4. (15 min) Discuss areas of composite figures
    • Pass out the "areas of composite figures" handout
    • Follow the discussion in that handout and have the students work the problems on it. This handout constitutes the in-class exercise.
  5. Hand out homework as students successfully complete the in-class exercise.