Power Lines

Power Lines is a free National Grid game. Students build the network that carries electricity from power stations to towns, a steelworks, a city and an island: overhead lines on poles and pylons, transformers to change the voltage, and underground or undersea cables where pylons aren’t allowed. Every network is solved like a real one. The current in each line comes from the power it carries (P = I × V), the energy wasted heating it is P = I² × R, and every line has a current it can’t safely go above. Send too much power at too low a voltage and the line glows red-hot, or so much voltage is lost on the way that the power never arrives.

How to play

Each level is a map. Choose a line from the toolbar at the bottom, then drag from the power station’s yard (the grey square with the yellow ring) to the place that needs power. Lines join the middles of the squares, across, up, down or diagonally. Where two voltages meet you need a transformer: choose the transformer tool and tap the square. Places come to life when they’re powered, and moving dots show the power flowing. Then press Switch on. Turn on Numbers to see the current in every line, the power it wastes and the voltage each place receives.

Each level earns up to three stars: one for a network that works, two for staying within the budget, and three for matching the cheapest design we know.

The levels

#	Level	Years	Big idea
1	Switch On	9	Power lines carry energy: P = IV
2	Far Away Farm	9	Long lines waste energy: P = I²R
3	Step Up, Step Down	10	Transformers and transmission voltages
4	The Steelworks	10	Current ratings and 400 kV lines
5	Two Towns	10–11	Networks: currents add at a junction
6	The National Park	11	Underground cables cost more
7	The Big City	11–12	The grid’s hierarchy of voltages
8	Wind at Sea	12–13	Offshore wind and undersea cables

Tips for teachers

• Year 9: before anyone builds Far Away Farm, ask the class to work out the current an 11 kV line needs to carry 2 MW (I = P ÷ V), then let them try it and see what happens.
• Years 10–11: Step Up, Step Down and The Steelworks show why the National Grid uses transformers and very high voltages. Ask students to compare the current and the wasted power at 33 kV and 132 kV with the Numbers button.
• Years 12–13: Two Towns and The Big City are real design problems: where to split a line, and when a separate small line is cheaper than tapping the big one. Wind at Sea adds the cost of undersea cable.

Every level ends with a short “What you learned” summary you can use as a plenary.