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Science lesson plan · 5th grade (Year 6 in England) · 45 minutes

Mass before and after: sealed and open containers

Materials and their properties

CCSS NGSS.5-PS1-2England: KS2 Y5 Properties and changes of materialsEngland: KS3 Chemistry: Chemical reactions

Objective and success criteria

Students will: Mass before and after: sealed and open containers.

  • 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: Conservation of mass

Leads to: the next skill in this area.

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 · 5 min

  • Quick retrieval from earlier learning (Conservation of mass). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. 50 g of chocolate is melted in a bowl. What is the mass of the melted chocolate, in g? → 50 gPrompt: Does a change of state add or remove any material?
  2. In a sealed flask, 47 g of one chemical reacts with 20 g of another. What is the total mass of the products, in g? → 67 gPrompt: In a closed container, atoms are only rearranged.
  3. Vinegar and bicarbonate of soda (baking soda) react in an open beaker. The mass falls from 195 g to 192.4 g. What mass of gas escaped, in g? → 2.6 gPrompt: Mass is not destroyed. Where did the missing mass go?

Hook · 5 min

  • Pass round objects made of different materials and ask why each one was chosen.
  • Share the objective: Mass before and after: sealed and open containers. 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: 165 g of water and 15 g of salt are stirred until the salt dissolves. What is the total mass?
  • Step 1: 165 + 15 = 180
  • Step 2: So the answer is: 180 g
  • Answer: 180 g
  • 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. 210 g of water and 25 g of salt are stirred until the salt dissolves. What is the total mass? → 235 gPrompt: Nothing is added or taken away.
  2. Vinegar and baking soda are mixed inside a sealed plastic bottle on a balance. They fizz and make a gas. The mass before was 225 g. What is the mass after the fizzing stops? → 225 gPrompt: Can the gas escape?

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. A sealed bag of 175 g of ice is left until all the ice has melted. What is the mass of the bag of water now (ignore the bag)? → 175 gPrompt: Melting changes the state, not the amount of matter.
  2. Rust forms on an iron nail. The rusty nail has MORE mass than the clean nail. Why? (Rust is always heavier than anything. / The nail grew longer. / Rust is made from nothing. / Oxygen from the air joined with the iron.) → Oxygen from the air joined with the iron.Prompt: Where did the extra particles come from?

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: Conservation of mass.
  • 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

  • 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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Mass before and after: sealed and open containers

Name

Date

Score/ 8

  1. Question 1

    Rust forms on an iron nail. The rusty nail has MORE mass than the clean nail. Why?

    • A. The nail grew longer.
    • B. Rust is made from nothing.
    • C. Rust is always heavier than anything.
    • D. Oxygen from the air joined with the iron.

  2. Question 2

    180 g of water and 20 g of salt are stirred until the salt dissolves. What is the total mass?

    Answerg

  3. Question 3

    Vinegar and baking soda are mixed in an OPEN cup on a balance. They fizz and 6 g of gas escapes into the air. The mass before was 288 g. What does the balance show after the fizzing stops?

    Answerg

  4. Question 4

    A burning candle on a balance gets lighter. Has matter been destroyed?

    • A. No, the wax has turned into gases that escaped into the air.
    • B. Yes, the flame eats the wax.
    • C. No, the balance is broken.
    • D. Yes, burning destroys matter.

  5. Question 5

    195 g of water and 40 g of salt are stirred until the salt dissolves. What is the total mass?

    Answerg

  6. Question 6

    Vinegar and baking soda are mixed inside a sealed plastic bottle on a balance. They fizz and make a gas. The mass before was 188 g. What is the mass after the fizzing stops?

    Answerg

  7. Question 7

    A sealed flask of water is weighed, heated until some water boils into steam, then weighed again with the lid still on. What happens to the mass?

    • A. It becomes zero.
    • B. It stays the same.
    • C. It goes up.
    • D. It goes down.

  8. Question 8

    A sealed bag of 110 g of ice is left until all the ice has melted. What is the mass of the bag of water now (ignore the bag)?

    Answerg

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Answer key: Mass before and after: sealed and open containers

  1. 1. D. Oxygen from the air joined with the iron.

  2. 2. 200 g

  3. 3. 282 g

  4. 4. A. No, the wax has turned into gases that escaped into the air.

  5. 5. 235 g

  6. 6. 188 g

  7. 7. B. It stays the same.

  8. 8. 110 g