Energy

Energy - Objectives

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What do students study in KS3? Where have they come from?

What is energy? In Physics/Biology/Chemistry What ideas do pupils have about energy?

Where could we start in Year 7?

Which teaching models could we use?

How could we approach teaching energy resources?

Energy in the National Curriculum KS3

3 Range and content This section outlines the breadth of the subject on which teacher should draw when teaching the key concepts and key processes.

The study of science should include:

3.1Energy, electricity and forces

a.

energy can be transferred usefully, stored, or dissipated, but cannot b.

c.

be created or destroyed forces are interactions between objects and can affect their shape and motion electric current in circuits can produce a variety of effects.

 Explanatory note:

such as fuel cells.

Energy: This includes the properties and behaviour of light and sound, renewable energy resources and emerging technologies

Energy in Physics KS3/4

Sound, light and waves

Electricity and magnetism

Prior teaching related to energy

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Pupils have learned some material in Key Stage 2 science that underpins Key Stage 3 Look at the handout – suggest how each of the Key Stage 2 objectives is related to the teaching of energy in Key Stage 3

What is energy?

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Look at cards on your desk As a group decide whether you agree/disagree with each statement, or you are not sure Try to come to a consensus

The Physicist’s View

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Energy is conserved Energy spreads out spontaneously and is less useable Energy can be stored and transferred The deliberate transfer of energy from one location to another is what the physicist calls work Energy does ‘NOT’ make things go.

Energy - Common Misconceptions

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Energy is a substance

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Whereas in reality - energy is an abstraction – may have some basis in the ’caloric’ theory Energy makes things go

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No - Forces make things start moving. Energy exists in many different forms

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There are only really two forms of energy

»

Kinetic Energy

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Potential Energy Energy comes from fuels

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The ‘chemical energy of a lump of a coal’ is a property of the whole system the fuel and the oxygen Heat is a form of energy

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It has been argued that we should not use ‘heat’ as a noun, but talk about ‘heating’ as a process

Carbon dioxide + water + salts Light Carbohydrate in Plants Biologist's View Carbohydrate in Animals Oxygen + Glucose Mov ement Biosynthesis Biotransport Bioluminescence Sound/electrical

Carbon dioxide + water Heat

The Chemist’s View

BOND BREAKING

ENERGY SUPPLIED

C + 4H + 4O (g) (g) (g)

Carbon, oxygen and hydrogen atoms BOND MAKING

ENERGY RELEASED

CH + 2O 4(g) 2(g)

methane + oxygen

CO + 2H O 2(g) 2 (g)

carbon dioxide + water vapour

Identifying children’s alternative conceptions: Concept Cartoons

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Look at the concept cartoon What is the misconception it illustrates?

Could this be investigated using a practical investigation? What would pupils do?

If not, how else could you approach teaching this?

Why concept cartoons work

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They help make learners’ ideas explicit They challenge and develop learners’ ideas They apply scientific ideas in everyday situations They promote discussion For more able pupils they can provide cognitive conflict which helps to clarify ideas They help legitimise alternative viewpoints – reduce the threat of giving the ‘wrong’ answer

Children’s Conceptualisation of Energy

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Vitamins give you energy Fit people have a lot of energy I did not have any energy left after doing cross country Energy is power My dog has a lot of energy, he runs around all the time Energy is like a force We cannot live without energy I am out of energy Everything has energy to make it go Sugar is a food which gives you energy When I go for a run, I use up all my energy Electricity can give you energy.

Some misconceptions

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Energy is a fluid or ingredient Energy is used up Energy is fuel Energy makes things happen

A starting point in Year 7

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It is suggested that we should move from familiar contexts to the less familiar Hence a possible teaching sequence is Energy in food Energy in fuel Electricity from fossil fuels/alternative resources

The energy content of food

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Look at the labels on handout 2.9

Burn each of the four types of food Match the label to the food Explain your choice – which piece of information on the label helped you decide?

How could this be extended into an investigation?

How could you collect valid and reliable data?

Comparing the energy content of different foods

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Use the food labels provided Look at the energy content per 100 g of the foods Attach the labels to the washing line in a way that enables you to compare the amount of energy stored in each Now look at the mystery foods and discuss in your group where you think these foods belong When you have made up your mind about the mystery foods, collect an answer sheet from your tutor What would you need to think about if running this activity with Year 7 classes? Management/learning

An introduction to energy conservation as an accounting system

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Look at handout 2.13, page 1, and answer the questions on page 2

Loop card game

Lunch

What is energy?

‘ … there is a certain quantity, which we call energy, that does not change in all the manifold changes which nature undergoes. That is a most abstract idea, because it is a mathematical principle: it says that there is a numerical quantity, which does not change when something happens. It is not a description of a mechanism, or anything concrete: it is just a strange fact that we can calculate some number and when we finish watching nature go through her tricks and calculate that number again it is the same.’ Richard Feynman

Dennis the Menace (adapted from Richard Feynman)

Imagine a child, perhaps “Dennis the Menace” who has blocks which are absolutely indestructible, and cannot be divided into pieces. Each is the same as the other. Let us suppose that he has 28 blocks. His mother puts him with his 28 blocks into a room at the beginning of the day. At the end of the day, being curious, she counts the blocks very carefully, and discovers a phenomenal law- no matter what he does with the blocks, there are always 28 remaining! This continues for a number of days until one day there are only 27 blocks, but a little investigating shows that there is one under the rug - she must look everywhere to be sure that the number of blocks has not changed. One day, the number appears to change - there are only 26 blocks. Careful investigation reveals that the window was open, and upon looking outside, the other two blocks are found.....

Different models for teaching energy

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Look at the pictures Choose which description A, B or C most closely matches what you would say to pupils Record it on the handout 3.4 ‘Task H Response sheet’

The model you chose

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Mainly A = transformation model Mainly B = transfer model Mainly C = hybrid

Energy transformation

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Heat Light Sound Nuclear Kinetic Potential

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Gravitational Elastic Chemical Electrical Describe a bungee jump using the transformation model

Difficulties with the transformation model:

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Gives the impression that energy must be transformed when work is done; Plethora of terms does nothing to improve conceptual understanding – clutter; Causes confusion about what is a process by which energy is transferred and what is a type of energy

What do physicists want students to know?

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Potential energy and kinetic energy are sufficient to describe everyday situations Mechanical working, heating and electrical working are three processes by which energy is transferred: Energy transferred mechanically is W = Fd Energy transferred thermally is W = mcT Energy transferred electrically is W = QV

The ‘energy transfer’ model

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In this model the energy is located in one place, and when something happens energy is transferred from that place to another by a process.

Typical use of language: ‘The energy in the battery is transferred to the bulb by electricity and then from the bulb to the surroundings by light. Some energy is transferred to the surroundings by heating.’ ‘Energy from the Sun is transferred to the leaf cells by light.’ ‘Energy is transferred from the reacting chemicals to the surroundings by heating and light.’ ‘A weightlifter transfers energy from his muscles to the bar by lifting (moving) his arms.’

Energy transfers in an electric torch

Cell

electric current heating light

Filament bulb

heating

Energy in surroundings Energy in surroundings

Slide 5.8

A Sankey diagram showing energy transfers in an electric torch

Cell Bulb Surroundings

Light Electric current Heating Heating

Surroundings

Slide 5.9

Using tokens with Sankey diagrams

Slide 5.10

Helping pupils to use the idea of energy conservation as an accounting system

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Choose one of the energy stories on handout 5.12

Use the squared paper and tokens supplied to make a Sankey diagram representing the energy transfers in your chosen story What would you need to think about if using this activity with children? Modifications/management/learning?

The usefulness of Sankey diagrams

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How does using blocks or tokens with Sankey diagrams help pupils to understand: Transfer of energy; Conservation of energy; Dissipation of energy; Energy efficiency?

What are the limitations of using Sankey diagrams in this way?

Energy Circus

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a) b) At each station think about how you would describe what happens in terms of The energy transformation model The energy transfer model

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What would you ask children to record?

What do you need to think about when organising a circus of experiments/stations?

Energy resources

Energy in the UK

The Energy Bill 2012 -2013 aims to close a number of coal and nuclear power stations over the next two decades, to reduce dependence on fossil fuels and has financial incentives to reduce energy demand. Government climate change targets are to produce 30% of electricity from renewable sources by 2020, to cut greenhouse gas emissions by 50% on 1990 levels by 2025 and by 80% on 1990 levels by 2050.

Task 1

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Put the blue cards in rank order (or diamond) An envoy visits another group to compare – discuss any differences The envoy returns – do you want to make any changes?

Podcast: Today programme ‘Airline travel is not sacrosanct’

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Listen to the podcast How might you use podcasts in the classroom?

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http://castroller.com/podcasts/BestOfToday/1220584

Task 2

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Read the purple cards which describe ways of reducing CO 2 emissions Choose the option you think is the best Make a TV advert promoting it

Energy - Objectives

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What do students study in KS3? Where have they come from?

What is energy? In Physics/Biology/Chemistry What ideas do pupils have about energy?

Where could we start in Year 7?

Which teaching models could we use?

How could we approach teaching energy resources?

Useful websites

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www.sep.org.uk

www.iop.org

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www.ase.org.uk

www.standards.dfes.gov.uk/secondary/keystage 3/all/respub/sc_energy http://www.talkphysics.org/