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Math lesson plan · 8th grade (Year 9 in England) · 45 minutes

Speed, density and other rates

Ratio and proportion

CCSS 7.RP.A.1CCSS HSN.Q.A.1England: KS3 RatioEngland: GCSE Foundation Ratio

Objective and success criteria

Students will: Speed, density and other rates.

  • 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: Unit rates; Divide decimals

Leads to: the next skill in this area.

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

Warm-up · 5 min

  • Quick retrieval from earlier learning (Unit rates; Divide decimals). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. 9 notebooks cost $126. What is the cost of one notebook? (Type the number only.) → 14Prompt: A unit rate is the amount for ONE.
  2. 67.2 ÷ 8 = ? → 8.4Prompt: Divide as with whole numbers.
  3. Fatima travels 63 km in 3 hours at a steady speed. How far does Fatima travel in one hour? → 21Prompt: Find the distance for one hour.

Hook · 5 min

  • Share a recipe for 4 people and ask how much is needed for 6.
  • Share the objective: Speed, density and other rates. 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: A train travels at 50 km/h for 1.5 hours. How far does it travel, in km?
  • Step 1: 50 × 1.5 = 75 km
  • Answer: 75
  • 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. A train travels at 26 km/h for 2.5 hours. How far does it travel, in km? → 65Prompt: Distance = speed × time.
  2. How many minutes does it take to drive 120 km at an average speed of 120 km/h? Round to the nearest minute. → 60Prompt: Time = distance ÷ speed (this gives hours).

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 cyclist covers 60 km in 2 hours. What is the average speed in km/h? → 30Prompt: Speed = distance ÷ time.
  2. How many minutes does it take to drive 208 km at an average speed of 48 km/h? Round to the nearest minute. → 260Prompt: Time = distance ÷ speed (this gives hours).

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: Unit rates.
  • 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

  • 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-8.

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

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Speed, density and other rates

Name

Date

Score/ 8

  1. Question 1

    How many minutes does it take to drive 201 km at an average speed of 90 km/h? Round to the nearest minute.

    Answer

  2. Question 2

    A cyclist covers 450 km in 3 hours. What is the average speed in km/h?

    Answer

  3. Question 3

    How many minutes does it take to drive 195 km at an average speed of 40 km/h? Round to the nearest minute.

    Answer

  4. Question 4

    A train travels at 20 km/h for 4 hours. How far does it travel, in km?

    Answer

  5. Question 5

    How many minutes does it take to drive 92 km at an average speed of 90 km/h? Round to the nearest minute.

    Answer

  6. Question 6

    A cyclist covers 100 km in 2 hours. What is the average speed in km/h?

    Answer

  7. Question 7

    How many minutes does it take to drive 92 km at an average speed of 48 km/h? Round to the nearest minute.

    Answer

  8. Question 8

    A cyclist covers 420 km in 3 hours. What is the average speed in km/h?

    Answer

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Answer key: Speed, density and other rates

  1. 1. 134

  2. 2. 150

  3. 3. 293

  4. 4. 80

  5. 5. 61

  6. 6. 50

  7. 7. 115

  8. 8. 140