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Math lesson plan · 6th grade (Year 7 in England) · 45 minutes

Area of shapes made from rectangles and triangles

Geometry

CCSS 6.G.A.1England: KS3 Geometry and measuresEngland: GCSE Foundation Geometry and measures

Objective and success criteria

Students will: Area of shapes made from rectangles and triangles.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Area of composite rectilinear shapes; Area of triangles

Leads to: the next skill in this area.

Materials: Rulers and protractors, Squared or dotted paper, Shape cut-outs, Mini whiteboards and pens, Printed student sheet (below).

Warm-up · 5 min

  • Quick retrieval from earlier learning (Area of composite rectilinear shapes; Area of triangles). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. An L-shape is made by cutting a 6 yd by 4 yd rectangle from the corner of a 12 yd by 7 yd rectangle. What is the area of the L-shape, in yd²? → 60Prompt: Find the area of the big rectangle.
  2. A garden is made of two rectangles: 2 ft × 3 ft and 6 ft × 4 ft. What is the total area, in ft²? → 30Prompt: Find the area of each rectangle.
  3. An L-shape is made by cutting a 3 cm by 2 cm rectangle from the corner of a 9 cm by 10 cm rectangle. What is the area of the L-shape, in cm²? → 84Prompt: Find the area of the big rectangle.

Hook · 5 min

  • Show a photo of a building, a tile pattern or a road sign and ask what shapes and angles students can spot.
  • Share the objective: Area of shapes made from rectangles and triangles. Read the success criteria together.

I do: model it · 10 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: An L-shaped room is a 15 m by 7 m rectangle with a 9 m by 3 m rectangle missing from one corner. What is its floor area, in m²?
  • Step 1: 15 × 7 = 105
  • Step 2: 9 × 3 = 27
  • Step 3: 105 − 27 = 78 m²
  • Answer: 78
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 10 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. An L-shaped room is a 15 m by 8 m rectangle with a 6 m by 3 m rectangle missing from one corner. What is its floor area, in m²? → 102Prompt: Find the area of the big rectangle.
  2. A house-shaped sign is a 6 cm wide, 6 cm tall rectangle with a triangle on top. The triangle has the same base and is 5 cm tall. What is the total area, in cm²? → 51Prompt: Split the shape into a rectangle and a triangle.

You do: independent practice · 10 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 5 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. A rectangular pond is 7 m by 3 m. A path 1 m wide goes all the way around it. What is the area of the path, in m²? → 24Prompt: The outside rectangle is 7 + 2 × 1 long and 3 + 2 × 1 wide.
  2. A house-shaped sign is a 10 cm wide, 9 cm tall rectangle with a triangle on top. The triangle has the same base and is 3 cm tall. What is the total area, in cm²? → 105Prompt: Split the shape into a rectangle and a triangle.

Watch out for

  • Thinking a square turned on its corner is no longer a square.
  • Reading the wrong scale on a protractor.

Support and stretch

Support

  • Review first: Area of composite rectilinear shapes.
  • Use concrete materials: rulers and protractors.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-6.

Free lesson plan from eurekami.com/lesson-plan-builder

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Area of shapes made from rectangles and triangles

Name

Date

Score/ 8

  1. Question 1

    A rectangular pond is 5 m by 8 m. A path 2 m wide goes all the way around it. What is the area of the path, in m²?

    Answer

  2. Question 2

    A house-shaped sign is a 8 cm wide, 3 cm tall rectangle with a triangle on top. The triangle has the same base and is 3 cm tall. What is the total area, in cm²?

    Answer

  3. Question 3

    An L-shaped room is a 15 m by 9 m rectangle with a 9 m by 4 m rectangle missing from one corner. What is its floor area, in m²?

    Answer

  4. Question 4

    A rectangular pond is 9 m by 4 m. A path 2 m wide goes all the way around it. What is the area of the path, in m²?

    Answer

  5. Question 5

    A house-shaped sign is a 16 cm wide, 5 cm tall rectangle with a triangle on top. The triangle has the same base and is 3 cm tall. What is the total area, in cm²?

    Answer

  6. Question 6

    An L-shaped room is a 14 m by 9 m rectangle with a 9 m by 6 m rectangle missing from one corner. What is its floor area, in m²?

    Answer

  7. Question 7

    A rectangular pond is 12 m by 3 m. A path 1 m wide goes all the way around it. What is the area of the path, in m²?

    Answer

  8. Question 8

    A house-shaped sign is a 6 cm wide, 7 cm tall rectangle with a triangle on top. The triangle has the same base and is 3 cm tall. What is the total area, in cm²?

    Answer

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Answer key: Area of shapes made from rectangles and triangles

  1. 1. 68

  2. 2. 36

  3. 3. 99

  4. 4. 68

  5. 5. 104

  6. 6. 72

  7. 7. 34

  8. 8. 51