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Science lesson plan · 8th grade (Year 9 in England) · 30 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 · 4 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 ×10 eyepiece lens and a ×40 objective lens. What is the total magnification? → 400Prompt: Combine the two lenses.
  2. Convert 11 L into mL. → 11000 mLPrompt: How many mL are in 1 L?
  3. A cell is 0.01 mm wide. It is viewed at ×100. How wide is the image, in mm? → 1 mmPrompt: magnification = image size ÷ actual size

Hook · 3 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 · 7 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 · 6 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 1.5 mm long. How long is it in micrometres (µm)? (1 mm = 1000 µm) → 1500 µmPrompt: Micrometres are smaller units, so the number gets bigger.
  2. A bacterium is 0.5 µm long. What is this in nanometres (nm)? (1 µm = 1000 nm) → 500 nmPrompt: Nanometres are smaller units.

You do: independent practice · 7 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 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. A structure is 7 µm wide. How wide is it in millimetres (mm)? (1 mm = 1000 µm) → 0.007 mmPrompt: Millimetres are bigger units, so the number gets smaller.
  2. A bacterium is 2 µm long. What is this in nanometres (nm)? (1 µm = 1000 nm) → 2000 nmPrompt: Nanometres are smaller units.

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

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Measure tiny things in mm, µm and nm

Name

Date

Score/ 6

  1. Question 1

    A cell is 0.01 mm long. How long is it in micrometres (µm)? (1 mm = 1000 µm)

    Answerµm

  2. Question 2

    A virus particle is 20 nm across. What is this in micrometres (µm)? (1 µm = 1000 nm)

    Answerµm

  3. Question 3

    A structure is 2 µm wide. How wide is it in millimetres (mm)? (1 mm = 1000 µm)

    Answermm

  4. Question 4

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

    Answerµm

  5. Question 5

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

    Answernm

  6. Question 6

    A cell is 1.5 mm long. How long is it in micrometres (µm)? (1 mm = 1000 µm)

    Answerµm

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

  1. 1. 10 µm

  2. 2. 0.02 µm

  3. 3. 0.002 mm

  4. 4. 0.08 µm

  5. 5. 1500 nm

  6. 6. 1500 µm

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