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Science lesson plan · 5th grade (Year 6 in England) · 60 minutes

Reversible and irreversible changes

Materials and their properties

CCSS NGSS.2-PS1-4CCSS NGSS.5-PS1-4England: KS2 Y5 Properties and changes of materials

Objective and success criteria

Students will: Reversible and irreversible changes.

  • 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: Dissolving and solutions

Leads to: Conservation of mass

Materials: A tray of everyday objects, Sorting hoops, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 6 min

  • Quick retrieval from earlier learning (Dissolving and solutions). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Is pepper soluble or insoluble in water? (soluble (dissolves in water) / insoluble (does not dissolve)) → insoluble (does not dissolve)Prompt: Imagine stirring it into a glass of water. Would it disappear from view?
  2. 20 g of sugar is dissolved in 250 g of water. What is the mass of the solution, in g? → 270 gPrompt: When something dissolves, does it disappear or is it still there?
  3. In salt water, what is the solvent? (water / the cup / salt / salt water) → waterPrompt: The solvent is the liquid that does the dissolving.

Hook · 6 min

  • Pass round objects made of different materials and ask why each one was chosen.
  • Share the objective: Reversible and irreversible changes. 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 change reversible or irreversible: melting butter?
  • Step 1: A reversible change can be undone, like melting, freezing, dissolving and evaporating.
  • Step 2: So the answer is: reversible
  • Answer: reversible
  • 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 change reversible or irreversible: boiling water into steam? (reversible / irreversible) → reversiblePrompt: Could you get the starting material back?
  2. Which change is reversible? (an iron nail rusting / cooking an egg / melting chocolate / burning wood) → melting chocolatePrompt: Changes of state and dissolving can be reversed.

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. Is this change reversible or irreversible: melting chocolate? (reversible / irreversible) → reversiblePrompt: Could you get the starting material back?
  2. Which change is irreversible? (freezing water into ice / melting chocolate / toasting bread / dissolving salt in water) → toasting breadPrompt: Changes of state and dissolving can be reversed.

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: Dissolving and solutions.
  • Use concrete materials: a tray of everyday objects.
  • 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: Conservation of mass.
  • 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-5.

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

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Reversible and irreversible changes

Name

Date

Score/ 8

  1. Question 1

    Is this change reversible or irreversible: toasting bread?

    • A. reversible
    • B. irreversible

  2. Question 2

    Which change is reversible?

    • A. melting chocolate
    • B. an iron nail rusting
    • C. baking a cake
    • D. burning wood

  3. Question 3

    How could you get salt back after dissolving it in water?

    • A. filter it
    • B. evaporate the water
    • C. freeze it
    • D. burn it

  4. Question 4

    Is this change reversible or irreversible: dissolving salt in water?

    • A. reversible
    • B. irreversible

  5. Question 5

    Melted candle wax sets hard again when it cools. This change is…

    • A. burning
    • B. irreversible
    • C. reversible
    • D. a chemical reaction

  6. Question 6

    Is this change reversible or irreversible: melting chocolate?

    • A. reversible
    • B. irreversible

  7. Question 7

    Which change is irreversible?

    • A. dissolving salt in water
    • B. cooking an egg
    • C. boiling water into steam
    • D. melting butter

  8. Question 8

    Which is a sign that a new material has been made?

    • A. bubbles of gas are given off when two substances mix
    • B. ice changes to water
    • C. a puddle dries up
    • D. sugar disappears in tea

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Answer key: Reversible and irreversible changes

  1. 1. B. irreversible

  2. 2. A. melting chocolate

  3. 3. B. evaporate the water

  4. 4. A. reversible

  5. 5. C. reversible

  6. 6. A. reversible

  7. 7. B. cooking an egg

  8. 8. A. bubbles of gas are given off when two substances mix