Science Activity : “Pirate Scientists” The changing states of water, filtration and evaporation Please also refer to http://www.getwet.org.uk/primary-school-stories Film: 1. Dunkirk: Overview & Evaluation of GetWET project Year 1 for background and discussion of some of the activities shown here.
The Big Idea: “Understanding the Importance of Water to Life”
Knowledge 1: “Know that some materials will dissolve in liquid to form a solution, and describe how to recover a substance from a solution.”
Knowledge 2: “Understand that some materials will dissolve in liquid to form a solution, and describe how to recover a substance from a solution.”
Knowledge 3: “Demonstrate that dissolving , mixing and changes of state are reversible changes.”
Vocabulary: Fresh, contaminated, pure, impurities, solution, soluble, insoluble, dissolve, distilled, vapour, evaporation, condensation, precipitation, filtration, desalination, deposits, aquifer, seeping, sandstone, porous, particles, reservoir, potable…
Candle stand & 2 small foil trays Laminated card or metal tray Please refer to http://www.getwet.org.uk/primary-school-stories film: 1. Dunkirk: Overview & Evaluation of GetWET project Year 1 Resources: ‘Sea water’ Funnel Filter paper Stirrer Glass jar Jug Tea light Matches Candle stand & 2 small foil trays Laminated card or metal tray Eye protectors Pirate costume &/or Lab coat (optional)
Stimulus: “A pirate ship runs aground on a desert island. There is no fresh water, no sign of rain, and not enough fruit to go round. How can the pirates survive without fresh water,…. or eating each other?!”
Take some sandy ‘sea water’ (mix a solution of tap water, sand & plenty of table salt together)…
Filter the solution through the funnel and filter paper to remove the sand – (the water is clean but not drinkable, it is a salt solution)…
Sand (which is tiny particles of rock and shell) doesn’t dissolve in water, so the pirates need to remove it from their water by this process of filtration…
Pour a small amount of the salty water (salt solution) into the tray, and heat it from underneath with the tea light… (NOTE it can get quite hot. The moment water turns into steam, it suddenly gets much hotter due to molecular activity – see drama work on molecular activity.)
As the water evaporates, hold the laminate over the steam at an angle, trapping the water vapour... it should run down into the second foil tray – the condensed water is called distilled water.
The salt should be left on the first tray as a deposit, and the distilled, pure water should run into the second tray, to create a small reservoir of drinkable (potable) water. (Distilled water can be used in domestic steam irons to stop small deposits being left on the iron or on clothes. Ordinary tap water has chemicals and salts dissolved in it, and these can be removed when it is evaporated and distilled, as in our experiment).
This is how our crew of pirates would be able to ensure they had fresh, clean water to drink through the processes of filtration, evaporation and condensation.
The following slides provide links to related topics which you may wish to explore with your class. See also Resource 18, A Long Walk to Water.
Related topics 1: Papplewick Connection How water filtrates through rock into underground fresh water reservoirs and aquifers e.g. the pure fresh water that is pumped from Papplewick is held in aquifers under the ground. Rainfall has seeped into the ground over hundreds and thousands of years, and any impurities in the water (such as earth micro-organisms, or animal droppings) are filtered out of the water by the porous Bunter Sandstone, in the same way the salt was filtered in the experiment, making it pure and safe to drink http://en.wikipedia.org/wiki/Bunter_(geology)
Related topics 2: How the water cycle includes evaporation, condensation and precipitation (sea and land)
Related topics 3: Salt reclamation Related topics 3: Salt reclamation. A practical use of the process of water evaporation to remove salts is the tradition of reclaiming salt from the sea in hot countries, going back many thousands of years http://en.wikipedia.org/wiki/Sea_salt
Marakkanam, TAMIL Nadu, INDIA
How is this process different from obtaining salt from mines, and who is involved in these processes? (Extension - How is the process of obtaining sugar from beet (e.g. UK) and sugar cane (e.g. Caribbean) different, and who is involved in these processes?)
Related topics 4: Human geography and politics Modern day pirates - The effect on people of climate change, water poverty and pollution
How can water shortages create the conditions for modern piracy. (e. g How can water shortages create the conditions for modern piracy? (e.g. in the Horn of Africa). How does the state of our environment (such as global warming) affect people who depend on the natural environment to survive (such as fishermen), and what are the choices open to them if their traditional livelihoods are affected or destroyed, (or overfished?) How can understanding why people may do things that we think are ‘wrong’ alter our view of what they are doing?...
Related Topic 5 - Water shortages with a Papplewick Connection Rosmery is a Bolivian water activist who visited Papplewick in 2013. She particularly highlighted the issues for women and children in accessing clean water. Have a look at the politics of water in Bolivia and other South American countries: https://climate.earthjournalism.net/2015/12/02/long-walks-for-water-in-bolivias-great- chaco/ https://www.wearewater.org/en/ancestral-culture-to-save-the-water-of-lake- titicaca_253217 Also see Resource 14: Bolivia