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Math lesson plan · 1st grade (Year 2 in England) · 45 minutes

Spot measuring mistakes: gaps and overlaps

Measurement

CCSS 1.MD.A.2England: Y1 Measurement

Objective and success criteria

Students will: Spot measuring mistakes: gaps and overlaps.

  • 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: Measure with same-size units and compare unit sizes

Leads to: the next skill in this area.

Materials: Rulers, scales and measuring jugs, Clock faces, Conversion chart, Mini whiteboards and pens, Printed student sheet (below).

Warm-up · 5 min

  • Quick retrieval from earlier learning (Measure with same-size units and compare unit sizes). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. A grown-up measures a table and gets 11 hand-spans. Grace's hand is bigger. Will Grace count more or fewer hand-spans? (More / Fewer / The same) → FewerPrompt: The table does not change.
  2. Jamal measured a book with paper clips and got 6. Grace measured the same book with cubes and got 10. Which unit is longer? (The paper clip / The cube) → The paper clipPrompt: The book is the same length both times.
  3. A grown-up measures a table and gets 9 hand-spans. Ana's hand is smaller. Will Ana count more or fewer hand-spans? (More / Fewer / The same) → MorePrompt: The table does not change.

Hook · 5 min

  • Ask the class to estimate the length of the room or the weight of a bag before measuring it.
  • Share the objective: Spot measuring mistakes: gaps and overlaps. 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: Kofi measured a shelf with cubes but left gaps between them. Will Kofi's number be too big or too small?
  • Step 1: Gaps mean fewer cubes are counted: too small.
  • Step 2: Too small
  • Answer: Too small
  • 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. Jamal measured a shelf with cubes but let them overlap. Will Jamal's number be too big or too small? (Too big / Too small / Just right) → Too bigPrompt: Overlapping cubes cover less length each.
  2. What is the right way to measure a window sill with cubes? (Line them up end to end with no gaps or overlaps, starting at one end / Use cubes of different sizes / Spread the cubes out with gaps to use fewer / Pile the cubes on top of each other in the middle) → Line them up end to end with no gaps or overlaps, starting at one endPrompt: Every bit of the length must be covered exactly once.

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. Chloe measured a shelf with cubes but left gaps between them. Will Chloe's number be too big or too small? (Too big / Too small / Just right) → Too smallPrompt: The gaps cover some of the shelf without a cube.
  2. What is the right way to measure a window sill with paper clips? (Line them up end to end with no gaps or overlaps, starting at one end / Spread the paper clips out with gaps to use fewer / Use paper clips of different sizes / Pile the paper clips on top of each other in the middle) → Line them up end to end with no gaps or overlaps, starting at one endPrompt: Every bit of the length must be covered exactly once.

Watch out for

  • Measuring from the end of the ruler instead of zero.
  • Converting units the wrong way (multiplying instead of dividing).

Support and stretch

Support

  • Review first: Measure with same-size units and compare unit sizes.
  • Use concrete materials: rulers, scales and measuring jugs.
  • 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

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Spot measuring mistakes: gaps and overlaps

Name

Date

Score/ 8

  1. Question 1

    Ravi measured a shelf with cubes but let them overlap. Will Ravi's number be too big or too small?

    • A. Too big
    • B. Too small
    • C. Just right

  2. Question 2

    What is the right way to measure a lunch box with cubes?

    • A. Line them up end to end with no gaps or overlaps, starting at one end
    • B. Use cubes of different sizes
    • C. Pile the cubes on top of each other in the middle
    • D. Spread the cubes out with gaps to use fewer

  3. Question 3

    Fatima measured a shelf with cubes but let them overlap. Will Fatima's number be too big or too small?

    • A. Too big
    • B. Too small
    • C. Just right

  4. Question 4

    What is the right way to measure a window sill with cubes?

    • A. Use cubes of different sizes
    • B. Spread the cubes out with gaps to use fewer
    • C. Pile the cubes on top of each other in the middle
    • D. Line them up end to end with no gaps or overlaps, starting at one end

  5. Question 5

    Leo measured a shelf with cubes but left gaps between them. Will Leo's number be too big or too small?

    • A. Too big
    • B. Too small
    • C. Just right

  6. Question 6

    What is the right way to measure a desk with cubes?

    • A. Spread the cubes out with gaps to use fewer
    • B. Line them up end to end with no gaps or overlaps, starting at one end
    • C. Pile the cubes on top of each other in the middle
    • D. Use cubes of different sizes

  7. Question 7

    Ethan measured a shelf with cubes but let them overlap. Will Ethan's number be too big or too small?

    • A. Too big
    • B. Too small
    • C. Just right

  8. Question 8

    What is the right way to measure a rug with paper clips?

    • A. Spread the paper clips out with gaps to use fewer
    • B. Pile the paper clips on top of each other in the middle
    • C. Line them up end to end with no gaps or overlaps, starting at one end
    • D. Use paper clips of different sizes

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Answer key: Spot measuring mistakes: gaps and overlaps

  1. 1. A. Too big

  2. 2. A. Line them up end to end with no gaps or overlaps, starting at one end

  3. 3. A. Too big

  4. 4. D. Line them up end to end with no gaps or overlaps, starting at one end

  5. 5. B. Too small

  6. 6. B. Line them up end to end with no gaps or overlaps, starting at one end

  7. 7. A. Too big

  8. 8. C. Line them up end to end with no gaps or overlaps, starting at one end