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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. Where is DNA found in an animal cell? (outside the cell / in the chloroplasts / mainly in the nucleus / in the cell wall) → mainly in the nucleusPrompt: It is the control centre of the cell.
  2. Human body cells have 23 pairs of chromosomes. How many chromosomes are in a skin cell? → 46Prompt: Is this a gamete (sex cell) or a body cell?
  3. How many chromosomes are in a normal human body cell? (23 / 12 / 92 / 46 (23 pairs)) → 46 (23 pairs)Prompt: They come in pairs, one of each pair from each parent.

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 halves the chromosome number (23 in humans). (mitosis / meiosis) → meiosisPrompt: Which one makes sex cells (gametes)?
  2. A bacterium divides into two every 30 minutes. Starting with one cell, how many cells are there after 3 hours (if none die)? → 64Prompt: 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. 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?
  2. Mitosis or meiosis? It produces genetically different cells. (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

    Why must gametes have half the normal number of chromosomes?

    • A. So they can swim faster
    • B. Because they are smaller
    • C. So the baby has no chromosomes
    • D. So the fertilised egg has the full number again

  2. Question 2

    Mitosis or meiosis? It makes four gametes.

    • A. mitosis
    • B. meiosis

  3. Question 3

    A bacterium divides into two every 20 minutes. Starting with one cell, how many cells are there after 1.666667 hours (if none die)?

    Answer

  4. Question 4

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

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

  5. Question 5

    Mitosis or meiosis? It halves the chromosome number (23 in humans).

    • A. mitosis
    • B. meiosis

  6. Question 6

    A bacterium divides into two every 20 minutes. Starting with one cell, how many cells are there after 2 hours (if none die)?

    Answer

  7. Question 7

    Mitosis or meiosis? It makes two identical cells.

    • A. mitosis
    • B. meiosis

  8. Question 8

    What is an advantage of sexual reproduction?

    • A. It produces variation, which helps a species survive changes
    • B. It makes identical offspring
    • C. It is faster than asexual reproduction
    • D. It needs only one parent

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Answer key: Mitosis and meiosis

  1. 1. D. So the fertilised egg has the full number again

  2. 2. B. meiosis

  3. 3. 32

  4. 4. D. asexual reproduction

  5. 5. B. meiosis

  6. 6. 64

  7. 7. A. mitosis

  8. 8. A. It produces variation, which helps a species survive changes