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Math lesson plan · 7th grade (Year 8 in England) · 60 minutes

Solve proportions

Ratio and proportion

CCSS 7.RP.A.2CCSS 7.RP.A.3England: KS3 Ratio, proportion and rates of changeEngland: GCSE Foundation Ratio

Objective and success criteria

Students will: Solve proportions.

  • 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: Proportional relationships

Leads to: Solve real-world proportion problems

Materials: Bar models, Double number lines, Ratio tables, Mini whiteboards and pens, Printed student sheet (below).

Warm-up · 6 min

  • Quick retrieval from earlier learning (Proportional relationships). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Is this relationship proportional? x: 1, 8, 10 → y: 6, 48, 60 (Yes, proportional / No, not proportional) → Yes, proportionalPrompt: Find y ÷ x for each pair.
  2. Grace can type 28 words in 4 minutes. At the same rate, how many words in 15 minutes? → 105Prompt: Find the words per minute first.
  3. Is this relationship proportional? x: 1, 4, 6 → y: 4, 16, 24 (Yes, proportional / No, not proportional) → Yes, proportionalPrompt: Find y ÷ x for each pair.

Hook · 6 min

  • Share a recipe for 4 people and ask how much is needed for 6.
  • Share the objective: Solve proportions. 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: Solve: x / 9 = 4 / 3
  • Step 1: 3 × 3 = 9
  • Step 2: x = 4 × 3 = 12
  • Answer: x = 12
  • 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. Solve: x / 36 = 4 / 6 → x = 24Prompt: What is 6 multiplied by to get 36?
  2. Solve: 2 / 12 = x / 24 → x = 4Prompt: Cross-multiply.

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. Solve: 2 / 3 = 6 / n → n = 9Prompt: Compare the numerators: how many times bigger?
  2. Solve: x / 10 = 4 / 5 → x = 8Prompt: What is 5 multiplied by to get 10?

Watch out for

  • Adding the same amount to both parts instead of multiplying.
  • Mixing up part-to-part and part-to-whole ratios.

Support and stretch

Support

  • Review first: Proportional relationships.
  • Use concrete materials: bar models.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Move on to: Solve real-world proportion problems.
  • 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-7.

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

eurekami

Solve proportions

Name

Date

Score/ 8

  1. Question 1

    Solve: 8 / 7 = 56 / n

    n =

  2. Question 2

    Solve: 6 / 5 = x / 15

    x =

  3. Question 3

    Solve: x / 50 = 4 / 10

    x =

  4. Question 4

    Solve: 7 / 3 = 98 / n

    n =

  5. Question 5

    Solve: 6 / 9 = 54 / y

    y =

  6. Question 6

    Solve: x / 9 = 2 / 3

    x =

  7. Question 7

    Solve: 9 / 7 = 72 / n

    n =

  8. Question 8

    Solve: 7 / 6 = 91 / y

    y =

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Answer key: Solve proportions

  1. 1. n = 49

  2. 2. x = 18

  3. 3. x = 20

  4. 4. n = 42

  5. 5. y = 81

  6. 6. x = 6

  7. 7. n = 56

  8. 8. y = 78