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Stefan visit a huge hi-tech greenhouse in Kent that grows cucumbers all year round. He meets Judy Whittaker who explains how they harvest water from the roof of the greenhouse, collect it in a reservoir and use it instead of tapwater to water their plants. In a demonstration, Stefan pours water from one container into another to explain how the same volume of water can come in lots of different shapes. Using a metre square frame he shows that for every millimetre of rain that falls on a square metre or roof we get a litre of water. Rob James helps him calculate how much water can be collected from the greenhouse roof that is 61,000 square metres. Stefan finds out that it depends on the rainfall but on average is 35 million litres per year. Stefan then meets a group of children from Peatmoor Primary School who talk about the water they need for their big ecogarden and show him their own rain harvesting project using the garden shed. Next Stefan helps them to calculate how much water they can collect from their main school roof using a scale plan of the school.
This clip is from:
First broadcast:
27 March 2012

Classroom Ideas

The children can be asked to work out this measurement of the school roof using a scale drawing of the school. They can find the monthly and annual rainfall in your local area from the internet to calculate how much rain could be harvested. How big would your school water storage tank have to be? What would be the size of a water storage tank for a month, or a year? Challenge the children to calculate how many months or years it would take for the storage tank to be bigger than your school.