# 04Calculating energy everywhere

En04TA of the Energy topic
• ## 01 Building Sankey diagramsEn04TAnugget01 Activity

### Representing different powers

What the activity is for

The purpose of this activity is to introduce the conventions of, and pupils to acquire familiarity with, Sankey diagrams. These diagrams allow us to describe processes in terms of the rates at which energy is shifting down various pathways. Ultimately this will require calculations, but for now estimates are enough to get the conversations started. The interactive object allows you to build Sankey diagrams for a number of given situations, and then to construct your own.

There is an important choice to be made: you'll have to decide whether you want to talk about processes that:

• are happeningâ€”so essentially about power and therefore best represented with Sankey arrows
• have happenedâ€”so essentially about snapshot to snapshot, and so best represented with bars showing the quantities of energy

Because of this essential distinction, each resource is provided in two forms.

What to prepare

• a data projector or interactive whiteboard and this interactive object

Power suggestions

• a car travelling along a motorway
• a leaf photosynthesising
• A bicycle freewheeling

Energy suggestions

• A sprung toy which has jumped into the air
• a bicycle which has freewheeled to a halt
• A car which has braked to a stop

What happens during this activity

This activity should be conducted as a teacher-led interactive demonstration using a data projector. Discuss the various situations you choose and use the interactive object with pupils, guiding their views as to stores and pathways. Use the controls to implement your decisions for the values of the power, explaining that the thickness of the arrows in the Sankey diagram represents the power in the pathway.

By the end of the demonstration, pupils should be familiar with the key features of Sankey diagrams and be in a position to start sketching their own diagrams.

• ## 02 An energy ladderEn04TAnugget02 Activity

### Getting to grips with the joule

What the activity is for

The purpose of this activity is to enable pupils to build up some idea of the size of the joule unit of energy.

What to prepare

• a blank copy of the ladder, A3 or larger

Support sheet

What happens during this activity

Place the ladder on the wall, with a few key values on it, then populate it with energies to give a feeling for the size of the joule and the range of energies connected with human activity. You might like to draw attention to the rather special times scale up the side where each interval represents a factor of 10 in the quantity of energy.

You might direct the pupils to provide the examples, perhaps researched for homework. If you do this the pupils will need help converting values from calories (1 kilocalorie (kcal) is 4.2 kilojoule) or kilowatt-hours (1 kilowatt hour is 3,600,000 joule).

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