Deborah Herridge uses practical science to help children comprehend the vital role of water in our ecosystem..

Herridge, Deborah

English

Northumbria University Research Portal

56A thirst forWhen we run the tap and get a glass of water we tend to think of it as‘fresh’ – but is it? Ask the children how old they think the water in theirglass is. A few hours? Days? Weeks even? How about as old as the Earthitself? Although the water we drink may have fallen as rain only a fewdays ago, it is the same water that the dinosaurs drank, or thatChristopher Columbus sailed across.Our planet has a limited amount of water. The water doesn’tdisappear, it gets used, reused and re-cycled time and time again in whatwe call the water cycle. The cycle has four main parts: evaporation,condensation, precipitation and collection. To help the children becomefamiliar with this new vocabulary, set up four ‘stations’ around the schoolyard. The children are going to become water particles on the journeythrough the water cycle.  1Things are heating up as we move to the ‘evaporation’ station wherechildren can use swirly movements to suggest water warming,changing state from a liquid to a gas and moving freely around. 2‘Condensation’ is cool and here the children are getting colder,moving closer together in the cold air to form clouds. 3At the ‘precipitation’ stage, they join together as water droplets andfall back to Earth as rain, sleet or snow. 4Finally, at ‘collection’, they join together in rivers and oceans and thecycle starts again. Practice moving through the cycle and perfecting your own actions at each stage until the children are confident with the cycle and the new vocabulary.HOW OLD IS YOUR WATER?Drinking with dinosaursDeborah Herridge use practicalscience to help childrencomprehend the vital role ofwater in our ecosystem...Covering 70% of the Earth’s surface, water is one of our mostplentiful resources, and yet often the scarcest. Every living thingneeds it to stay alive and without the atomic pairing of hydrogenand oxygen our planet would be dry, dusty and lifeless. It is then, perhaps,surprising that water is the one resource we take completely for granted.Using these practical science activities, children will learn to see wateras a finite resource. By examining processes such as the water cycle andtranspiration, they will begin to understand that it is a precious substanceshared by people, animals and plants across the globe not just now but inthe future also.ECO SCHOOLS:WATER ACTIVITY 1Half fill a large, plastic fish tank or clear bowl withwarm, salty water (the sea). Put an empty tea-cup inthe centre of the tank so that the rim sits well abovethe surface of the water. Cover the top of the tank with plastic foodwrapping film and place several ice cubes in thecentre of the plastic; this cold area representsclouds. You’ll see that the plastic dips down towardsthe cup under the weight of the ice - though itshouldn’t be allowed to touch the rim. To encourage the salty ‘sea’water to evaporate,place the tank on a sunny windowsill. (Or for a fasterresult, train a couple of desk lamps on the water.) What do you see? Droplets of clear watershould gather and condense on the plastic belowthe ice and fall as precipitation into the cup beneath.Take a taste – hey presto, no salt!BUILD YOUR OWN WATER CYCLE...Around we goACTIVITY 2knowledgePlants take in water through their root system and lose it through their leaves in a process calledtranspiration. We can see this happening if we cover a branch of a shrub, tree or even a large pot plantwith a plastic bag and tie it securely so that the leaves are totally encased. After a few hours, take a lookat the bag; you should see that water has condensed on the inside. This is the water that the plant haslost through its leaves. You can build a mini biosphere by cutting the top off a pop bottle about 1/3 of the way down. Half fillthe base with compost, root some small plants in the soil and water. Put the bottle back together again, re-seal with sellotape and make sure the top is screwed on.You’ll be amazed how the plants grow with barely any intervention. They can happily survive by recyclingthe water in the bottle.You can measure transpiration by placing branches in a glass of water topped off with oil, which willprevent evaporation. Mark the level of the water with a pen; as the leaves transpire you will see the waterlevel drop over the course of the day. Do the plants with the biggest leaves lose the most water – I wonder?DO PLANTS SWEAT?As it transpires ACTIVITY 31.4 million children die every year as a result ofdiseases spread through unclean water or poorsanitation. That’s 4000 every day. In many areasof the world water is so polluted by industry orpoor sanitation that people are forced todrink dirty water.With the class, you can investigatehow water is purified by making a naturalfilter. Use scissors to cut the top off a popbottle. Take the bottom half and with apair of compasses, pierce some holesaround the sides near to the base. Put thebottle in a bowl and begin filling it with largepebbles to a depth of about8 cms. Then add a layer ofsmaller gravel, followed bya layer of coarse sand andfinally a layer of fine sand. In a jug, mix somegarden compost with waterand pour it into your filter. Asthe water passes through, thedirt and soil gets trapped inthe layers. The water thatcomes out of the holes in thebottom should be muchcleaner than the water in thejug. This shows children howwater is naturally filtered as itflows through the ground.CLEANING UP OUR ACT...Pollution problemsACTIVITY 457In the UK, if we want clean water we just turn on a tap – easy! If weneed to get rid of dirty water we flush it away or pour it down the drain.In many other parts of the world children aren’t so fortunate. Ask pupils to research water consumption in our country andcontrast it with how water is consumed in developing nations. Howmuch water do we use? How much do we waste? As a school, discuss if there are any ways in which you can reducewater consumption. What would our lives be like if we had only half thewater we have now? Challenge the children to design a ‘desert’ gardenusing only those plants that require very little water to flourish. Research the life and work of English cartoonist William HeathRobinson (1872-1944) Can the children devise a water savinginvention in the style of Heath Robinson? Offer a prize for the mostinventive and original!Water Aid’s Splish Splash Flush DVD is available free to schoolsand youth groups. With a running time of 13 minutes, it’s perfect for usein assemblies. For your copy, please email schools@wateraid.org.HOW CAN YOUR SCHOOL CONSERVE WATER?What a wasteACTIVITY 5Children recreatecondensation in the watercycle, getting colder andmoving together

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