Presentation on theme: "This is a Roast Beef Sandwich"— Presentation transcript:
1 This is a Roast Beef Sandwich FACILITATOR CARD:Two slices of white bread, 2 slices roast beef (about 30g each), mayo and mustard.Take “guess-timates” of how much water went into the production of this sandwich.How much water was used to make this sandwich?
2 Water use in Agriculture All over the world, in every country, agriculture uses the most amount of water.A United Nations study of global averages calculated that 70% of total water consumption goes to agriculture, mostly irrigation.By contrast the domestic use of water in homes is only 5% to 10% of total water consumption, depending on how “developed” the country is.Facilitator Notes:Draw a pie chart on the board, showing 70% vs. 5 or 10%.
3 Beef Cattle on the FarmTo get beef, we need to raise a cow! Some cows weigh up to 900kg. It takes 13,500,000 litres of water to raise a cow for the land, feed, drinking water, and cleaning.To roughly calculate the amount of water we actually need, let’s calculate the weight of beef we need:=30g slices X 2 slices each X number of people.Now use that value to calculate the amount of water:[13,500,000L/900kg] X weight (kg)= L water needed for our sandwichesFacilitator Notes: Do the math on the board.For example: 30 students x 30g x 2 = 1800g of beef = 1.8kg[13,500,000L/ 900kg] x 1.8kg = 27,000L of water to add to the tallyRaising cows for beef uses the highest amount of water compared with other agricultural product
4 Let’s compare water usage… Ask your classmates to guess the order! For 1kg of…Beef = 15 cubic meters of waterLamb = 10 cubic meters of waterChicken = 6 cubic meters of waterPalm Oil = 2 cubic meters of waterWheat = 1.5 cubic meters of waterOranges = 1 cubic meter of waterBeans = 1 cubic meter of waterCarrots = 1 cubic meter of waterPotatoes = 1 cubic meter of waterFacilitator Notes:Have the student who receives this ‘card’ to write the options on the board. Classmates can then guess the order of water usage from most to least.Beef is really high on the water usage list!
5 Now let’s go to the bakery to buy our bread. Water use in the BakeryNow let’s go to the bakery to buy our bread.Let’s say we need two loaves of sliced bread which each take approximately 53 litres of water to make when you include the cleaning and industrial processes required in a commercial bakery.=another 106 litres of waterAdd 106L to your tally
6 Water use in processed foods: Now let’s go to the store to buy the mayonnaise and mustard. These are processed foods made in commercial food manufacturing plants.We need to add in the water used for keeping the factories and their transportation trucks clean to a safe standard, as well as what’s actually used in the production process.=32 litres per package,one for the mayo and mustard.Add 64L to your tally
7 Water in the KitchenWe have all of our ingredients now, so we can go to our kitchen to prepare the sandwiches.First, we must wash our hands. Anyone who prepares food for others in a commercial kitchen must wash their hands for a minimum of 20 seconds to ensure they are thoroughly clean and won’t make people sick by contaminating the food.= another 3 litres of water per person.e.g. Add 90L for a 30 person class.
8 Cleaning the KitchenOur kitchen needs to be cleaned each day using three 5 gallon buckets: one to wash with soapy water, one to rinse the soap and food away and the last one with bleach and water to kill any bacteria on the preparation table surfaces and equipment.=15 gallons=68 litres of water.Add 68L of water to your tally
9 To Make Our Beef Sandwiches Totals: e.g litres or gallons for 30 sandwiches= 508 litres or 112 gallons for each sandwich= 20 X 25L buckets, or 254 2L pop bottlesHow many litres of water in total?