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Science lesson plan · 6th grade (Year 7 in England) · 60 minutes

Continuous and discontinuous variation

Cells, genetics and evolution

CCSS NGSS.MS-LS3-2CCSS NGSS.SEP 4England: KS3 Biology: Inheritance, chromosomes, DNA and genes

Objective and success criteria

Students will: Continuous and discontinuous variation.

  • 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: Inherited and environmental characteristics

Leads to: Use twins and clones to separate genes from environment

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 (Inherited and environmental characteristics). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Is this characteristic inherited or environmental: a suntan? (inherited (from parents) / environmental (from life)) → environmental (from life)Prompt: Were you born with it, or did it happen during life?
  2. Identical twins have the same genes. One becomes much stronger. Why? (Strength is never affected by exercise. / Their genes changed into different ones. / They are not really twins. / The environment, such as exercise, made a difference.) → The environment, such as exercise, made a difference.Prompt: What can be different if their genes are the same?
  3. Inheritance: which statement is true? (A scar is an environmental characteristic. / Children are always exact copies of one parent. / If a parent loses a finger, its babies are born without that finger. / The language you speak is inherited.) → A scar is an environmental characteristic.Prompt: Which things can be passed on in genes?

Hook · 6 min

  • Show a microscope image of cells and ask what students think they are looking at.
  • Share the objective: Continuous and discontinuous variation. 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: Is this continuous or discontinuous variation: height?
  • Step 1: Continuous variation can take any value in a range, so it is measured.
  • Step 2: So the answer is: continuous
  • Answer: continuous
  • 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. Is this continuous or discontinuous variation: height? (continuous / discontinuous) → continuousPrompt: Can it have any value, or only a few set categories?
  2. Five students measured their heights in cm: 158, 175, 176, 161, 148. What is the range of their heights, in cm? → 28 cmPrompt: The range shows how spread out the data are.

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. Which of these is an example of discontinuous variation? (heart rate / body mass / arm length / ABO blood group) → ABO blood groupPrompt: Which one has only a few fixed categories?
  2. Five students measured their heights in cm: 154, 162, 149, 185, 167. What is the range of their heights, in cm? → 36 cmPrompt: The range shows how spread out the data are.

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: Inherited and environmental characteristics.
  • 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: Use twins and clones to separate genes from environment.
  • 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-6.

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

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Continuous and discontinuous variation

Name

Date

Score/ 8

  1. Question 1

    A class records everyone's blood group. Which graph should they draw?

    • A. a line graph
    • B. a bar chart with a separate bar for each group
    • C. a histogram with no gaps
    • D. a scatter graph

  2. Question 2

    Five students measured their heights in cm: 158, 140, 162, 169, 181. What is the range of their heights, in cm?

    Answercm

  3. Question 3

    Is this continuous or discontinuous variation: height?

    • A. continuous
    • B. discontinuous

  4. Question 4

    Which of these is an example of discontinuous variation?

    • A. body mass
    • B. heart rate
    • C. ABO blood group
    • D. arm length

  5. Question 5

    Five students measured their heights in cm: 165, 172, 181, 157, 147. What is the range of their heights, in cm?

    Answercm

  6. Question 6

    Is this continuous or discontinuous variation: leaf length?

    • A. continuous
    • B. discontinuous

  7. Question 7

    Five students measured their heights in cm: 183, 172, 154, 161, 142. What is the range of their heights, in cm?

    Answercm

  8. Question 8

    Five students measured their heights in cm: 178, 143, 172, 160, 152. What is the range of their heights, in cm?

    Answercm

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Answer key: Continuous and discontinuous variation

  1. 1. B. a bar chart with a separate bar for each group

  2. 2. 41 cm

  3. 3. A. continuous

  4. 4. C. ABO blood group

  5. 5. 34 cm

  6. 6. A. continuous

  7. 7. 41 cm

  8. 8. 35 cm