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Science lesson plan · 9th grade (Year 10 in England) · 60 minutes

Mitosis and meiosis

Cells, genetics and evolution

CCSS NGSS.HS-LS1-4CCSS NGSS.MS-LS3-2England: KS4 Combined Science: Cell biologyEngland: KS4 Combined Science: Evolution, inheritance and variation

Objective and success criteria

Students will: Mitosis and meiosis.

  • 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: DNA, genes and chromosomes

Leads to: The cell cycle and the stages of mitosis; Count chromosomes after mitosis, meiosis and fertilisation

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 (DNA, genes and chromosomes). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Rosalind Franklin's X-ray image helped scientists discover… (penicillin / the first vaccine / the shape of the Earth / the structure of DNA) → the structure of DNAPrompt: Watson and Crick used her data.
  2. Human body cells have 23 pairs of chromosomes. How many chromosomes are in an egg cell? → 23Prompt: Is this a gamete (sex cell) or a body cell?
  3. What is a gene? (a type of cell / a disease / a section of DNA that codes for a protein / a whole chromosome) → a section of DNA that codes for a proteinPrompt: Genes are found along chromosomes.

Hook · 6 min

  • Show a microscope image of cells and ask what students think they are looking at.
  • Share the objective: Mitosis and meiosis. 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: Mitosis or meiosis? It produces genetically different cells.
  • Step 1: Meiosis makes four genetically different gametes with half the chromosomes.
  • Step 2: So the answer is: meiosis
  • Answer: meiosis
  • 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. Mitosis or meiosis? It happens in the ovaries and testes. (mitosis / meiosis) → meiosisPrompt: Which one makes sex cells (gametes)?
  2. A bacterium divides into two every 60 minutes. Starting with one cell, how many cells are there after 3 hours (if none die)? → 8Prompt: How many divisions happen in that time?

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. Why must gametes have half the normal number of chromosomes? (So the fertilised egg has the full number again / Because they are smaller / So the baby has no chromosomes / So they can swim faster) → So the fertilised egg has the full number againPrompt: What happens when an egg and sperm join?
  2. Mitosis or meiosis? It halves the chromosome number (23 in humans). (mitosis / meiosis) → meiosisPrompt: Which one makes sex cells (gametes)?

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: DNA, genes and chromosomes.
  • 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

  • Move on to: The cell cycle and the stages of mitosis; Count chromosomes after mitosis, meiosis and fertilisation.
  • 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-9.

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

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Mitosis and meiosis

Name

Date

Score/ 8

  1. Question 1

    Before a cell divides by mitosis, what must it do?

    • A. copy its DNA
    • B. halve its chromosomes
    • C. stop respiring
    • D. lose its nucleus

  2. Question 2

    A bacterium divides into two every 20 minutes. Starting with one cell, how many cells are there after 1 hours (if none die)?

    Answer

  3. Question 3

    Mitosis or meiosis? It keeps the full number of chromosomes (46 in humans).

    • A. mitosis
    • B. meiosis

  4. Question 4

    A bacterium divides into two every 60 minutes. Starting with one cell, how many cells are there after 3 hours (if none die)?

    Answer

  5. Question 5

    Which type of reproduction produces offspring that are genetic clones of the parent?

    • A. asexual reproduction
    • B. sexual reproduction
    • C. meiosis
    • D. fertilisation

  6. Question 6

    A bacterium divides into two every 30 minutes. Starting with one cell, how many cells are there after 2 hours (if none die)?

    Answer

  7. Question 7

    Mitosis or meiosis? It produces genetically different cells.

    • A. mitosis
    • B. meiosis

  8. Question 8

    A bacterium divides into two every 60 minutes. Starting with one cell, how many cells are there after 5 hours (if none die)?

    Answer

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Answer key: Mitosis and meiosis

  1. 1. A. copy its DNA

  2. 2. 8

  3. 3. A. mitosis

  4. 4. 8

  5. 5. A. asexual reproduction

  6. 6. 16

  7. 7. B. meiosis

  8. 8. 32