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Science lesson plan · 5th grade (Year 6 in England) · 30 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 · 4 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. 120 g of water is frozen in a sealed tub. What is the mass of the ice, in g? → 120 gPrompt: Does a change of state add or remove any material?
  2. In a sealed flask, 81 g of one chemical reacts with 10 g of another. What is the total mass of the products, in g? → 91 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 212 g to 210.9 g. What mass of gas escaped, in g? → 1.1 gPrompt: Mass is not destroyed. Where did the missing mass go?

Hook · 3 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 · 7 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 · 6 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. 130 g of water and 10 g of salt are stirred until the salt dissolves. What is the total mass? → 140 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 195 g. What is the mass after the fizzing stops? → 195 gPrompt: Can the gas escape?

You do: independent practice · 7 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 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Rust forms on an iron nail. The rusty nail has MORE mass than the clean nail. Why? (Oxygen from the air joined with the iron. / Rust is always heavier than anything. / Rust is made from nothing. / The nail grew longer.) → Oxygen from the air joined with the iron.Prompt: Where did the extra particles come from?
  2. Vinegar and baking soda are mixed in an OPEN cup on a balance. They fizz and 5 g of gas escapes into the air. The mass before was 268 g. What does the balance show after the fizzing stops? → 263 gPrompt: Can the gas escape?

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/ 6

  1. Question 1

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

  2. Question 2

    275 g of sand and 10 g of iron filings are mixed together. 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 4 g of gas escapes into the air. The mass before was 199 g. What does the balance show after the fizzing stops?

    Answerg

  4. Question 4

    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. Oxygen from the air joined with the iron.
    • D. Rust is always heavier than anything.

  5. Question 5

    270 g of water and 50 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 236 g. What is the mass after the fizzing stops?

    Answerg

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

  1. 1. B. It stays the same.

  2. 2. 285 g

  3. 3. 195 g

  4. 4. C. Oxygen from the air joined with the iron.

  5. 5. 320 g

  6. 6. 236 g