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Science lesson plan · 7th grade (Year 8 in England) · 30 minutes

Density

States of matter

CCSS NGSS.MS-PS1-2CCSS NGSS.5-PS1-3England: KS3 Physics: MatterEngland: KS4 Combined Science: Particle model of matter

Objective and success criteria

Students will: Density.

  • 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: The particle model

Leads to: Find density using water displacement

Materials: Ice, water and a kettle (teacher demo), Particle diagrams, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 4 min

  • Quick retrieval from earlier learning (The particle model). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Which state is described: particles in fixed positions that only vibrate? (solid / liquid / gas) → solidPrompt: How close are the particles, and how do they move?
  2. What happens to particles when a substance is heated? (They stop moving / They melt / They move faster / They get bigger) → They move fasterPrompt: Heating gives particles more energy.
  3. The particle model: which statement is NOT true? (Particles in a gas are much further apart than in a liquid. / Particles in a solid do not move at all. / Particles in a solid still vibrate. / There is empty space between gas particles.) → Particles in a solid do not move at all.Prompt: Do particles themselves change size?

Hook · 3 min

  • Show an ice cube melting and a kettle steaming and ask what is the same and what is different.
  • Share the objective: Density. 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: A block has a mass of 27 g and a volume of 10 cm³. What is its density, in g/cm³?
  • Step 1: density = mass ÷ volume
  • Step 2: 27 ÷ 10 = 2.7
  • Step 3: So the answer is: 2.7 g/cm³
  • Answer: 2.7 g/cm³
  • 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. A block has a mass of 45.2 g and a volume of 4 cm³. What is its density, in g/cm³? → 11.3 g/cm³Prompt: density = mass ÷ volume
  2. The density of olive oil is 0.91 g/cm³. Water's density is 1.0 g/cm³. Does a solid piece of olive oil float or sink in water? (floats / sinks) → floatsPrompt: Compare the density with water's density.

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. The density of steel is 7.8 g/cm³. Water's density is 1.0 g/cm³. Does a solid piece of steel float or sink in water? (floats / sinks) → sinksPrompt: Compare the density with water's density.
  2. A block has a mass of 1.6 g and a volume of 2 cm³. What is its density, in g/cm³? → 0.8 g/cm³Prompt: density = mass ÷ volume

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: The particle model.
  • Use concrete materials: ice, water and a kettle (teacher demo).
  • 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: Find density using water displacement.
  • 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-7.

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

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Density

Name

Date

Score/ 6

  1. Question 1

    The density of oak wood is 0.75 g/cm³. Water's density is 1.0 g/cm³. Does a solid piece of oak wood float or sink in water?

    • A. floats
    • B. sinks

  2. Question 2

    A cube has sides of 3 cm and a density of 7.9 g/cm³. What is its mass, in g?

    3 cm3 cm

    Answerg

  3. Question 3

    A block has a mass of 60 g and a volume of 50 cm³. What is its density, in g/cm³?

    Answerg/cm³

  4. Question 4

    The density of olive oil is 0.91 g/cm³. Water's density is 1.0 g/cm³. Does a solid piece of olive oil float or sink in water?

    • A. floats
    • B. sinks

  5. Question 5

    A cube has sides of 5 cm and a density of 7.9 g/cm³. What is its mass, in g?

    5 cm5 cm

    Answerg

  6. Question 6

    A block has a mass of 27 g and a volume of 10 cm³. What is its density, in g/cm³?

    Answerg/cm³

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Answer key: Density

  1. 1. A. floats

  2. 2. 213.3 g

  3. 3. 1.2 g/cm³

  4. 4. A. floats

  5. 5. 987.5 g

  6. 6. 2.7 g/cm³