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Energy
Energy - Objectives
What do students study in KS3 and 4?
What is energy?
What ideas do pupils have about energy?
Where could we start in Year 7?
Which teaching models could we use?
What are the different teaching energy resources?
Calculation of fuel uses and costs in the domestic context
•comparing energy values of different foods (from labels) (kJ) •comparing power ratings of appliances in watts (W, kW) •comparing amounts of energy transferred (J, kJ, kW hour) •domestic fuel bills, fuel use and costs •fuels and energy resources.
Energy in National Curriculum at KS3
Energy changes and transfers
•simple machines give bigger force but at the expense of smaller movement (and vice versa): product of force and displacement unchanged •heating and thermal equilibrium: temperature difference between two objects leading to energy transfer from the hotter to the cooler one, through contact (conduction) or radiation; such transfers tending to reduce the temperature difference: use of insulators •other processes that involve energy transfer: changing motion, dropping an object, completing an electrical circuit, stretching a spring, metabolism of food, burning fuels.
Energy in National Curriculum at KS3
Changes in systems
• energy as a quantity that can be quantified and calculated; the total energy has the same value before and after a change •comparing the starting with the final conditions of a system and describing increases and decreases in the amounts of energy associated with movements, temperatures, changes in positions in a field, in elastic distortions and in chemical compositions •using physical processes and mechanisms, rather than energy, to explain the intermediate steps that bring about such changes.
Energy in National Curriculum at KS3
Energy, electricity and radiations
7In their study of science, the following should be covered:
a. energy transfers can be measured and their efficiency calculated, which is important in considering the economic costs and environmental effects of energy use b. electrical power is readily transferred and controlled, and can be used in a range of different situations c. radiations, including ionising radiations, can transfer energy d. radiations in the form of waves can be used for communication.
Energy in National Curriculum at KS4 -2015
Energy
• energy changes in a system involving heating, doing work using forces, or doing work using an electric current: calculating the stored energies and energy changes involved• power as the rate of transfer of energy • conservation of energy in a closed system, dissipation • calculating energy efficiency for any energy transfers• renewable and non-renewable energy sources used on Earth, changes in how these are used.
Energy in National Curriculum at KS4 -2016
(Miller, 2003, ed. Sang)
ENERGY MAP
Sound, light and waves
(Hollins, 2003, ed. Sang)
Electricity and magnetism
(Soloman, 2003, ed. Sang)
What is energy?
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
Light
Carbon dioxide + water + salts
Carbohydrate in Plants
Carbohydrate in
Animals
Oxygen + Glucose
Movement Biosynthesis Biotransport Bioluminescence Sound/electrical
Carbon dioxide + water Heat
Biologist's View
The Chemist’s ViewC + 4H + 4O
(g) (g) (g)
CH + 2O4(g) 2(g)
CO + 2H O2(g) 2 (g)
BOND BREAKING
ENERGY SUPPLIEDBOND MAKING
ENERGYRELEASED
Carbon, oxygen and hydrogen atoms
methane + oxygen
carbon dioxide + water vapour
The Physicist’s View
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 MisconceptionsEnergy is a substance
• Whereas in reality - energy is an abstraction – may have some basis in the ’caloric’ theory
Energy makes things go• No - Forces make things start moving.
Energy exists in many different forms• There are only really two forms of energy
• Kinetic Energy• Potential Energy
Energy comes from fuels• The ‘chemical energy of a lump of a coal’ is a property of the whole
system - the fuel and the oxygenHeat is a form of energy
• It has been argued that we should not use ‘heat’ as a noun, but talk about ‘heating’ as a process
Children’s Conceptualisation of Energy Vitamins give you energyFit people have a lot of energyI did not have any energy left after doing cross countryEnergy is powerMy dog has a lot of energy, he runs around all the timeEnergy is like a forceWe cannot live without energyI am out of energyEverything has energy to make it goSugar is a food which gives you energyWhen I go for a run, I use up all my energyElectricity can give you energy.
Why concept cartoons workThey 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
A starting point in Year 7
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
Comparing the energy content of different foods
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
Task FAn introduction to energy conservation as an accounting system
Look at handout 2.13, page 1, and answer the questions on page 2
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 20 blocks. His mother puts him with his 20 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 20 remaining! This continues for a number of days until one day there are only 19 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 18 blocks. Careful investigation reveals that the window was open, and upon looking outside, the other two blocks are found.....
Energy transfers in an electric torch
electric current light
heating heatingCell Filament bulb
Energy in surroundings
Energy in surroundings
Slide 5.8
A Sankey diagram showing energy transfers in an electric torch
Slide 5.9
Electric current
Heating
Heating
Light
Cell Bulb Surroundings
Surroundings
Using tokens with Sankey diagrams
Slide 5.10
Helping pupils to use the idea of energy conservation as an accounting system
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
The usefulness of Sankey diagrams
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?
Different models for teaching energy
Look at the pictures
Choose which description A, B or C most closely matches what you would say to pupils
The model you chose
Mainly A = transformation model
Mainly B = transfer model
Mainly C = hybrid
Difficulties with the transformation model:
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 we want students to know?
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
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.’
Photocopy of example terms…
Institute OF PHYSICS
http://www.iop.org/education/teacher/support/spt/page_41531.html
Top BBC news story 21/9/15
This is so current!!!
http://www.bbc.co.uk/news/uk-england-somerset-34306997
Energy - Objectives
What do students study in KS3 and 4?
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?
What are the different teaching energy resources?
