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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: natural eye colour? (inherited (from parents) / environmental (from life)) → inherited (from parents)Prompt: Were you born with it, or did it happen during life?
  2. A plant grown in a dark cupboard is tall, thin and pale. Its seeds are planted in sunlight. The new plants are… (white, because their parent was in the dark / unable to grow / pale, because they inherit it / normal and green, because the pale look was caused by the environment) → normal and green, because the pale look was caused by the environmentPrompt: Is being pale passed on in the seeds?
  3. Inheritance: which statement is true? (A scar is an environmental characteristic. / If a parent loses a finger, its babies are born without that finger. / The language you speak is inherited. / Children are always exact copies of one parent.) → 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: Rhesus blood type (positive or negative)? (continuous / discontinuous) → discontinuousPrompt: Can it have any value, or only a few set categories?
  2. Five students measured their heights in cm: 167, 161, 177, 153, 148. What is the range of their heights, in cm? → 29 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. Height data for a large group of adults usually form which shape when plotted? (a bell-shaped curve (normal distribution) / two separate bars / a flat line / a straight rising line) → a bell-shaped curve (normal distribution)Prompt: Most people are near the middle; few are very tall or very short.
  2. Five students measured their heights in cm: 180, 159, 175, 158, 146. What is the range of their heights, in cm? → 34 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

    Is this continuous or discontinuous variation: pea seed shape (round or wrinkled)?

    • A. continuous
    • B. discontinuous
  2. Question 2

    Five students measured their heights in cm: 148, 183, 172, 163, 155. What is the range of their heights, in cm?

    Answercm

  3. Question 3

    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 scatter graph
    • D. a histogram with no gaps
  4. Question 4

    Is this continuous or discontinuous variation: height?

    • A. continuous
    • B. discontinuous
  5. Question 5

    Five students measured their heights in cm: 165, 146, 174, 176, 151. What is the range of their heights, in cm?

    Answercm

  6. Question 6

    Which of these is an example of discontinuous variation?

    • A. body mass
    • B. ABO blood group
    • C. arm length
    • D. heart rate
  7. Question 7

    Is this continuous or discontinuous variation: hand span?

    • A. continuous
    • B. discontinuous
  8. Question 8

    Five students measured their heights in cm: 175, 181, 141, 164, 154. What is the range of their heights, in cm?

    Answercm

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Answer key: Continuous and discontinuous variation

  1. 1. B. discontinuous

  2. 2. 35 cm

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

  4. 4. A. continuous

  5. 5. 30 cm

  6. 6. B. ABO blood group

  7. 7. A. continuous

  8. 8. 40 cm