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Science lesson plan · 9th grade (Year 10 in England) · 45 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 · 5 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. What shape is a DNA molecule? (a ring of six atoms / a cube / a double helix / a single straight line) → a double helixPrompt: It looks like a twisted ladder.
  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 · 5 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 · 10 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 · 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. Mitosis or meiosis? It makes four gametes. (mitosis / meiosis) → meiosisPrompt: Which one makes sex cells (gametes)?
  2. A bacterium divides into two every 20 minutes. Starting with one cell, how many cells are there after 1.666667 hours (if none die)? → 32Prompt: How many divisions happen in that time?

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

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

  2. Question 2

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

    Answer

  3. Question 3

    Mitosis or meiosis? It makes four gametes.

    • A. mitosis
    • B. meiosis

  4. Question 4

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

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

  5. Question 5

    A bacterium divides into two every 30 minutes. Starting with one cell, how many cells are there after 2.5 hours (if none die)?

    Answer

  6. Question 6

    Mitosis or meiosis? It makes two identical cells.

    • A. mitosis
    • B. meiosis

  7. Question 7

    Why must gametes have half the normal number of chromosomes?

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

  8. Question 8

    A bacterium divides into two every 60 minutes. Starting with one cell, how many cells are there after 4 hours (if none die)?

    Answer

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Answer key: Mitosis and meiosis

  1. 1. D. copy its DNA

  2. 2. 16

  3. 3. B. meiosis

  4. 4. A. asexual reproduction

  5. 5. 32

  6. 6. A. mitosis

  7. 7. B. So the fertilised egg has the full number again

  8. 8. 16