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Math lesson plan · 6th grade (Year 7 in England) · 30 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 · 4 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 5 yd by 3 yd rectangle from the corner of a 8 yd by 7 yd rectangle. What is the area of the L-shape, in yd²? → 41Prompt: Find the area of the big rectangle.
  2. A garden is made of two rectangles: 7 cm × 4 cm and 8 cm × 6 cm. What is the total area, in cm²? → 76Prompt: Find the area of each rectangle.
  3. An L-shape is made by cutting a 8 ft by 2 ft rectangle from the corner of a 12 ft by 6 ft rectangle. What is the area of the L-shape, in ft²? → 56Prompt: Find the area of the big rectangle.

Hook · 3 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 · 7 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 · 6 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 11 m by 6 m rectangle with a 5 m by 3 m rectangle missing from one corner. What is its floor area, in m²? → 51Prompt: Find the area of the big rectangle.
  2. A house-shaped sign is a 10 cm wide, 3 cm tall rectangle with a triangle on top. The triangle has the same base and is 2 cm tall. What is the total area, in cm²? → 40Prompt: Split the shape into a rectangle and a triangle.

You do: independent practice · 7 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 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. An L-shaped room is a 13 m by 8 m rectangle with a 3 m by 2 m rectangle missing from one corner. What is its floor area, in m²? → 98Prompt: Find the area of the big rectangle.
  2. A house-shaped sign is a 6 cm wide, 4 cm tall rectangle with a triangle on top. The triangle has the same base and is 2 cm tall. What is the total area, in cm²? → 30Prompt: 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/ 6

  1. Question 1

    An L-shaped room is a 8 m by 7 m rectangle with a 3 m by 4 m rectangle missing from one corner. What is its floor area, in m²?

    Answer

  2. Question 2

    A house-shaped sign is a 8 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?

    Answer

  3. Question 3

    A rectangular pond is 9 m by 5 m. A path 2 m wide goes all the way around it. What is the area of the path, in m²?

    Answer

  4. Question 4

    An L-shaped room is a 15 m by 8 m rectangle with a 9 m by 3 m rectangle missing from one corner. What is its floor area, in m²?

    Answer

  5. Question 5

    A house-shaped sign is a 10 cm wide, 8 cm tall rectangle with a triangle on top. The triangle has the same base and is 4 cm tall. What is the total area, in cm²?

    Answer

  6. Question 6

    A rectangular pond is 12 m by 7 m. A path 1 m wide goes all the way around it. What is the area of the path, in m²?

    Answer

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Answer key: Area of shapes made from rectangles and triangles

  1. 1. 44

  2. 2. 68

  3. 3. 72

  4. 4. 93

  5. 5. 100

  6. 6. 42