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Math lesson plan · 1st grade (Year 2 in England) · 60 minutes

Which shape does not belong, and why?

Geometry

CCSS 1.G.A.1England: Y1 GeometryEngland: Y2 Geometry

Objective and success criteria

Students will: Which shape does not belong, and why?.

  • 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: What makes a shape that shape?

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 · 6 min

  • Quick retrieval from earlier learning (What makes a shape that shape?). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Which is always true about every square? (It is big / It is blue / It points upwards / It has 4 equal straight sides and 4 square corners) → It has 4 equal straight sides and 4 square cornersPrompt: Colour, size and which way it faces can change.
  2. Which of these is a triangle? (A shape with 4 straight sides / A shape with 3 straight sides that meet at 3 corners / A shape with 3 straight sides that do not join up / A shape with 3 curved sides) → A shape with 3 straight sides that meet at 3 cornersPrompt: A triangle is a closed shape.
  3. Which is always true about every hexagon? (It points upwards / It has 6 straight sides / It is big / It is blue) → It has 6 straight sidesPrompt: Colour, size and which way it faces can change.

Hook · 6 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: Which shape does not belong, and why?. Read the success criteria together.

I do: model it · 12 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Which shape does not belong: square, triangle, rectangle?
  • Step 1: The triangle: it has 3 sides, the others have 4.
  • Answer: triangle
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 12 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. Which shape does not belong: hexagon, rectangle, square? (hexagon / rectangle / square) → hexagonPrompt: Count the sides of each shape.
  2. Which shape does not belong: square, triangle, circle? (square / triangle / circle) → circlePrompt: Count the sides of each shape.

You do: independent practice · 17 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 · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Which shape does not belong: triangle, square, rectangle? (triangle / square / rectangle) → trianglePrompt: Count the sides of each shape.
  2. Which shape does not belong: square, triangle, circle? (square / triangle / circle) → circlePrompt: Count the sides of each shape.

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: What makes a shape that shape?.
  • 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-1.

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

eurekami

Which shape does not belong, and why?

Name

Date

Score/ 8

  1. Question 1

    Omar sorts shapes into two groups: "has 4 sides" and "does not have 4 sides". Where does a triangle go?

    • A. Has 4 sides
    • B. Does not have 4 sides

  2. Question 2

    Which shape does not belong: square, rectangle, triangle?

    • A. square
    • B. rectangle
    • C. triangle

  3. Question 3

    Leo sorts shapes into two groups: "has 4 sides" and "does not have 4 sides". Where does a rectangle go?

    • A. Has 4 sides
    • B. Does not have 4 sides

  4. Question 4

    Which shape does not belong: triangle, square, circle?

    • A. triangle
    • B. square
    • C. circle

  5. Question 5

    Hana sorts shapes into two groups: "has 4 sides" and "does not have 4 sides". Where does a triangle go?

    • A. Has 4 sides
    • B. Does not have 4 sides

  6. Question 6

    Which shape does not belong: hexagon, circle, pentagon?

    • A. hexagon
    • B. circle
    • C. pentagon

  7. Question 7

    Kwame sorts shapes into two groups: "has 4 sides" and "does not have 4 sides". Where does a square go?

    • A. Has 4 sides
    • B. Does not have 4 sides

  8. Question 8

    Which shape does not belong: triangle, square, rectangle?

    • A. triangle
    • B. square
    • C. rectangle

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Answer key: Which shape does not belong, and why?

  1. 1. B. Does not have 4 sides

  2. 2. C. triangle

  3. 3. A. Has 4 sides

  4. 4. C. circle

  5. 5. B. Does not have 4 sides

  6. 6. B. circle

  7. 7. A. Has 4 sides

  8. 8. A. triangle