Why this is not a quiz
Every litre on your plate was rained on, pumped or piped somewhere upstream. Food companies are now asked to report those litres to buyers, lenders and regulators, and a shipment with no defensible water number is getting harder to sell. The method you are about to use on one dinner is the same method used on a whole supply chain: mass, a published coefficient, a named source, and an honest statement of what it leaves out.
You are not being tested on the answer. You are being tested on whether you can defend it.
Do this tonight
- Pick the dinner your family actually eatsNot the interesting one. The one that repeats. If you measure something unusual, the number tells you nothing about your household.
- Weigh one plate, item by itemRaw mass in grams for every ingredient on one person's plate. Rice, daal, oil, meat, vegetables. Write each one down separately — a total is useless to you.
- Look up the litres per kilogram for each itemSearch the ingredient plus "water footprint per kg". Write the number and the source beside it. A figure with no source does not count.
- Multiply, then addGrams ÷ 1000 × litres per kg, for every item. Add them up. That is the litres behind one plate.
- Find the biggest single barWhich one item carries most of the total? It is almost never the one people guess.
- Say what your number leaves outCooking water? Transport? Washing up? Name what you did not count. This is the step that separates a measurement from a guess.
litres_for_item = grams ÷ 1000 × litres_per_kg
litres_per_plate = sum of every item
litres_per_year = litres_per_plate × times you eat it a year
# and one line you must write by hand:
"This number does not include ______."
Post it, message it, or say it at the table. Three things only: the dish, the litres per plate, and the one item that carried the most. If you want to be checked, send it to us and we will tell you honestly whether the method holds up.
What happens if you keep going
Tonight you produced a number. A finished EAD project takes that number and does the harder half: you change exactly one thing — an ingredient swapped, a portion cut, a form of waste stopped — cook the same dish on three dates across three weeks, and measure whether the litres actually fell.
That second half is where the marks are, and where the honesty is. A well-measured failure scores higher than an unmeasured success. If your change did nothing, saying so clearly is worth more than a success you cannot prove.
The full six-week project, free
Twenty written steps, both routes, the marking rubric, and the exact questions you will be asked to defend it. Nothing to buy, nothing to sign up for.
Open the full project See the other elevenFor teachers
This page is a single-night version of the first act of one project. The complete set is twelve projects, 240 written steps, in two routes — one of which needs no computer, no internet and no electricity. Both booklets are free and complete, and the first year costs a school nothing including training one teacher.