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Science lesson plan · 8th grade (Year 9 in England) · 60 minutes

Measure tiny things in mm, µm and nm

Cells, genetics and evolution

CCSS NGSS.MS-LS1-1CCSS NGSS.SEP 5England: GCSE Combined Science: Cell biology (orders of magnitude)

Objective and success criteria

Students will: Measure tiny things in mm, µm and nm.

  • 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: Microscopes and magnification; Converting units

Leads to: the next skill in this area.

Materials: Microscope images or slides, Cell diagrams, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 6 min

  • Quick retrieval from earlier learning (Microscopes and magnification; Converting units). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. A microscope has a ×5 eyepiece lens and a ×10 objective lens. What is the total magnification? → 50Prompt: Combine the two lenses.
  2. Convert 5 L into mL. → 5000 mLPrompt: How many mL are in 1 L?
  3. A cell is 0.02 mm wide. It is viewed at ×500. How wide is the image, in mm? → 10 mmPrompt: magnification = image size ÷ actual size

Hook · 6 min

  • Show a microscope image of cells and ask what students think they are looking at.
  • Share the objective: Measure tiny things in mm, µm and nm. 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: A cell is 0.05 mm long. How long is it in micrometres (µm)? (1 mm = 1000 µm)
  • Step 1: 0.05 × 1000 = 50
  • Step 2: So the answer is: 50 µm
  • Answer: 50 µm
  • 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. A cell is 0.25 mm long. How long is it in micrometres (µm)? (1 mm = 1000 µm) → 250 µmPrompt: Micrometres are smaller units, so the number gets bigger.
  2. A virus particle is 20 nm across. What is this in micrometres (µm)? (1 µm = 1000 nm) → 0.02 µmPrompt: Is a micrometre bigger or smaller than a nanometre?

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. A structure is 40 µm wide. How wide is it in millimetres (mm)? (1 mm = 1000 µm) → 0.04 mmPrompt: Millimetres are bigger units, so the number gets smaller.
  2. A virus particle is 300 nm across. What is this in micrometres (µm)? (1 µm = 1000 nm) → 0.3 µmPrompt: Is a micrometre bigger or smaller than a nanometre?

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: Microscopes and magnification.
  • Use concrete materials: microscope images or slides.
  • 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/science/grade-8.

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

eurekami

Measure tiny things in mm, µm and nm

Name

Date

Score/ 8

  1. Question 1

    A bacterium is 1.5 µm long. What is this in nanometres (nm)? (1 µm = 1000 nm)

    Answernm

  2. Question 2

    A structure is 25 µm wide. How wide is it in millimetres (mm)? (1 mm = 1000 µm)

    Answermm

  3. Question 3

    A virus particle is 80 nm across. What is this in micrometres (µm)? (1 µm = 1000 nm)

    Answerµm

  4. Question 4

    A cell is 0.02 mm long. How long is it in micrometres (µm)? (1 mm = 1000 µm)

    Answerµm

  5. Question 5

    A virus particle is 300 nm across. What is this in micrometres (µm)? (1 µm = 1000 nm)

    Answerµm

  6. Question 6

    A cell is 0.002 mm long. How long is it in micrometres (µm)? (1 mm = 1000 µm)

    Answerµm

  7. Question 7

    A bacterium is 0.5 µm long. What is this in nanometres (nm)? (1 µm = 1000 nm)

    Answernm

  8. Question 8

    A virus particle is 120 nm across. What is this in micrometres (µm)? (1 µm = 1000 nm)

    Answerµm

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Answer key: Measure tiny things in mm, µm and nm

  1. 1. 1500 nm

  2. 2. 0.025 mm

  3. 3. 0.08 µm

  4. 4. 20 µm

  5. 5. 0.3 µm

  6. 6. 2 µm

  7. 7. 500 nm

  8. 8. 0.12 µm