Energy - Objectives What do students study in KS3? 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 electricity?
Energy in the National Curriculum KS3 from 2006 – what does the new NC for 2014 say? 3Range 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 be created or destroyed b. forces are interactions between objects and can affect their shape and motion c. electric current in circuits can produce a variety of effects. Explanatory note: Energy: This includes the properties and behaviour of light and sound, renewable energy resources and emerging technologies such as fuel cells.
Energy in Physics KS3/4
Sound, light and waves
Electricity and magnetism
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
The energy content of food: which food matches which label? 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 Look at the energy content per 100 g of the foods Attach the labels provided to the washing line in a way that enables you to compare the amount of energy stored in each Where do the mystery foods belong?
Introduction to energy as an accounting system
Use the ‘typical’ energy values provided to answer these questions: 1 How many chocolate bars would Eamonn need to eat to run a marathon? 2 Chris has a burger, chips and a can of drink for lunch. How far could he walk during the afternoon? 3 Chris’s friend Rifat has the same for lunch as Chris, but she sits still in class all afternoon. How much of the stored energy from her food is not needed during the afternoon? 4 What happens to the stored energy from food if we don’t need all of it to complete an activity? 5 The next day Rifat gets up early and goes for a jog. She doesn’t have time to eat any breakfast, but strangely she doesn’t seem to have a problem with not having enough energy for the run. How is this possible?
Some misconceptions Energy is a fluid or ingredient Energy is used up Energy is fuel Heat and temperature are the same thing Energy makes things happen
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 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 Mainly A = transformation model Mainly B = transfer model Mainly C = hybrid
Energy transformation Heat Light Sound Nuclear Kinetic Potential – Gravitational – Elastic – Chemical Electrical Describe a bungee jump using the transformation model Describe a bungee jump using the transformation model
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.’
Energy transfers in an electric torch electric current light heating Cell 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 Light Cell Bulb 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?
Energy in the UK The UK Government has set four goals for the country's energy policy: To put ourselves on a path to cut the UK’s CO2 emissions by some 60% by about 2050, with real progress by 2020; To maintain the reliability of energy supplies; To promote competitive markets in the UK and beyond, helping to raise the rate of sustainable economic growth and to improve our productivity; and To ensure that every home is adequately and affordably heated. For more information on sustainable development in the North West, see The main source for information in this document is Our Energy Challenge, DTI, Materials may be reproduced for teaching and non-profit purposes. Copyright, C. Porter, 2006.
Task 1 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?
Task 2 Read the purple cards which describe ways of reducing CO 2 emissions Choose the option you think is the best Make an advert promoting it
Useful resources QCA Schemes of work for KS3 science: uk/schemes2/secondary_science/?view=get uk/schemes2/secondary_science/?view=get ‘Teaching Secondary Physics’ by David Sang Talk Physics: Register and then download SPT materialshttp://www.talkphysics.org/ ‘Concept cartoons’ by Keogh and Naylor Association for science education: National Strategies materials: energy-tutors-pack energy-tutors-pack ‘Making Sense of Secondary Science’ by Ros Driver et al Teaching about Energy: outenergy.pdf outenergy.pdf Interactive simulations: