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Let's teach! Primary

Lesson 2

What happens when solids and liquids are heated and cooled?

Lesson Plan

Preparation

  • Lesson 5 of this unit should be completed before this lesson.
  • Provide some examples of the substances discussed on the student summary i.e. water, milk, honey, wood, fruit, sugar, margarine.
  • Collect the equipment needed by the investigation sheet, i.e. 5 identical bars of dairy milk chocolate, thermometer, 1 ovenproof tray, oven, 4 paper plates.
  • Preheat the oven to 180 degrees Celcius.

Curriculum links

  • Australian Curriculum: ACSSU046, ACSIS053, ACSIS054, ACSIS055, ACSIS057, ACSIS215, ACSIS058, ACSIS060
  • NSW Curriculum: ST2-6MW-S, ST2-1WS-S
  • Victorian Curriculum: VCSSU059, VCSIS070, VCSIS065, VCSIS066, VCSIS067, VCSIS068, VCSIS069, VCSIS071, VCSIS072
  • WA Curriculum: ACSSU046, ACSIS053, ACSIS054, ACSIS055, ACSIS057, ACSIS215, ACSIS058, ACSIS060

Suggested teaching strategies

  • Collaborative learning

Introduction

  • Though several of the scientific terms are revised in the text, before reading through the student pages, ensure students understand the terms ‘matter’, ‘states of matter’, ‘substance’, ‘solid’, ‘liquid’ etc. if Lesson 1 has not been taught.

Development

  • Provide students with printable versions of the student summary and worksheet. Have students complete the worksheet.
  • When completing the investigation sheet, have students discuss how they can ensure the test is fair or not (all chocolate bars must be identical).
  • The student summary and worksheet should be used together.

Differentiation

  • Students can work in a small group or as a whole class for the activity on the investigation sheet.

Conclusion

  • Once students have completed their experiment, encourage them to discuss with the rest of the class either teacher-led or students sharing with other groups.

Assessment

Worksheet answers

1. honey, milk, raw egg
2. Answers should indicate that margarine is a solid in the fridge or at room temperature. When heated, it becomes a liquid. When cooled it becomes a solid once more.
3. …a substance changes state and cannot be changed back again…
4. (a) No, irreversible (b) Yes, reversible
5. (a) False (b) False (c) False

Investigation sheet answers

Temperatures will vary, except for the oven which should show it has been preheated to 180 degrees celcius. (Obviously, the students will use the gauge as a guide and not actually use a thermometer!)
A summary of what should happen is provided below. Allow the students to touch the chocolate before recording to hlep them describe what happened. Digital photographs could be taken at appropriate intervals.
(a) The chocolate in the classroom should look the same and remain a solid and be at room temperature to touch.
(b) The chocolate in full sun will melt and become a thick liquid (at an interval depending on how hot the day is), could feel slightl warm if a hot day and be sticky and possibly quite runny to touch.
(c) Depending on the heat of the day, the chocolate may or may not partially or fully melt.
(d) Chocolate will take a very short time to melt. (Don’t allow it to stay too long in oven.) It may even bubble if it reaches boiling point. When first taken out of the oven it will be a runny liquid and quite warm to touch. (Take care it is not too hot for students to touch.)
(e) Chocolate will remain solid and cool to touch.

Student Pages

Science Year 3 Unit 2 Lesson 2 Intro 1
Lesson 2
What happens when solids and
liquids are heated and cooled?
Science Year 3 Unit 2 Lesson 2 Intro 2
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Lesson 2
What happens when solids and
liquids are heated and cooled?
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Science Year 3 Unit 2 Lesson 2 Slide 1

Matter is any material that takes up space and has mass (weight).

Liquids and solids are two states of matter.

Science Year 3 Unit 2 Lesson 2 Slide 2

Science _ Unit 2 – Lesson 2 – image

Science _ Unit 2 – Lesson 2 – image

Examples of liquids are water, milk and honey.

Wood, fruit and sugar are examples of solids.

Science Year 3 Unit 2 Lesson 2 Slide 3

A liquid can change into a solid and a solid can change into a liquid.

We call this changing sites.

Science Year 3 Unit 2 Lesson 2 Slide 4

For example, a tub of margarine is a solid in the fridge or at room temperature on the kitchen bench.

If it is heated in a microwave, it becomes a liquid.

If it is left to cool, it will become a solid once more.

Science Year 3 Unit 2 Lesson 2 Slide 5

When a substance changes state, it can sometimes change back.

This is called a reversible change.

No new substance is made.

Science Year 3 Unit 2 Lesson 2 Slide 6

If it can not be changed back again, it is called irreversible.

A new substance has been made.

Here are examples of each:

Science Year 3 Unit 2 Lesson 2 Slide 7

Science – Unit 2 – Lesson 2 – image – margarine

Reversible change

The margarine described before turned from a solid to a liquid through heating.

It turned back to a solid when it was cooled.

Science Year 3 Unit 2 Lesson 2 Slide 8

Irreversible change

Inside a raw egg is thick, liquid egg white and even thicker liquid yellow yolk.

Science Year 3 Unit 2 Lesson 2 Slide 9

If it is cracked onto a heated frying pan, it can be heated (cooked) until it becomes a solid fried egg. (Sometimes the yolk can be left a bit runny.)

It cannot become a raw egg again, even if it is left to cool.

Science Year 3 Unit 2 Lesson 2 Slide 10

Solids have different temperatures to which they need to be heated until they melt and become liquid.

Science Year 3 Unit 2 Lesson 2 Slide 11

Ice blocks become solid at 0° celsius.

As soon as they are taken out of the freezer at 0° degrees celsius, they gradually begin to melt.

Science Year 3 Unit 2 Lesson 2 Slide 12

A metal like gold takes an enormous amount of heat before it changes from solid to liquid - more than 1000° C

Science Year 3 Unit 2 Lesson 2 Slide 13

Liquids have different temperatures to which they need to be cooled until they harden and become solid.

Science Year 3 Unit 2 Lesson 2 Slide 14

Margarine that has been heated until it is a liquid will eventually become solid at room temperature.

It will happen more quickly if put in the fridge.

Science – Unit 2 – Lesson 2 – image – margarine

Science Year 3 Unit 2 Lesson 2 Slide 15

Science – Unit 2 – Lesson 2 – image – olive oil

Oils such as olive oil or sunflower oil need to be cooled a lot more by putting them in the freezer before they will become solid.

Science Year 3 Unit 2 Lesson 2 Final Slide
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Downloads

Student Summary

Summary of student page information

Worksheet

Activities for students to complete

Investigation Worksheet

An experiment to consolidate learnings

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