Agriculture & Climate · Project 1 of 12

The Sixty-Litre Dinner

How many litres of water are behind one dinner

Weigh tonight's dinner, then count the litres of water standing behind it that nobody at the table sees.

Six weeksNo equipment on the paper route 20 written stepsMarked out of 20Free forever
The question

How many litres of water and how many rupees stand behind one plate of a dinner you actually eat, and which single item carries most of both?

Every litre on your plate was rained on, pumped or piped somewhere upstream, and the food industry is now asked to report those litres to buyers, lenders and regulators. Water-footprint accounting is paid work in farming, food processing and export, because a shipment with no defensible water number is getting harder to sell. The method you use on one dinner is the method used on a whole supply chain: mass, a published coefficient, a cited source, and an honest statement of what the number leaves out.

Two acts. Find, then fix.

Every EAD project runs the same shape. The first act produces a number nobody in the room could previously state. The second act changes exactly one thing and proves whether that number moved.

Act 1 · Find
You take one dinner your household cooks anyway and account for it item by item: raw mass on one plate, rupees actually paid, and litres of water per kilogram taken from a published source you name beside the number. You also weigh what gets thrown away across seven days, because food thrown out carries its whole footprint with it.

A one-page costed problem statement carrying four lines: whose dinner, litres of water per plate, rupees per plate, and litres and rupees per year at the rate this household actually eats it. Beside it sits a bar chart of litres per item, largest bar first, and a source line against every coefficient used.

Act 2 · Fix
You change exactly one thing — an ingredient swapped, a portion cut, a shop changed, or one form of waste stopped — and cook the same dish on three dates across three weeks. Every weighing, price and source is repeated identically, so the only moving part is the change you named.

A four-bar chart of litres per plate, baseline against weeks one, two and three, with the mean after-figure, the difference in litres and rupees per year, a named list of confounders, and the household's recorded answer on whether the change stays.

What actually gets measured

The numberlitres of water behind one plate of one dinner, in litres per plate
BeforeRaw mass in grams of every ingredient on one plate, multiplied by a published litres-per-kilogram figure with its source recorded beside it, plus the litres attached to food weighed into the bin over the same seven days. Taken before anything is changed.
AfterThe identical dish measured the identical way on three dates across three weeks, using the same scale, the same divisor and the same published sources, reported as a mean with all three weeks shown separately.
The honest partA well-measured failure scores higher than an unmeasured success. If the number did not move, say so and explain why.

Every step, written out

Twenty steps in total — ten to find the number, ten to fix it. Pick the route that matches what your school actually has.

A scale, a notebook and a pen produce the same litres figure; the only thing borrowed from outside is the published coefficient table, and you borrow that from a person, a library or a printed page and write its source on it.
You need: A kitchen scale, or a marked measuring cup and a one-litre bottle for anything liquid · A notebook ruled into six columns with a pen and a ruler: item, grams, rupees, litres per kilogram, source, litres on plate · The household's shop receipts, or a card carrying prices copied at the shop counter · A hand-copied or printed water-footprint table with the source written across the top, obtained from a library, a college, a print shop or a person with a connection · Squared paper for the bar charts, drawn to a stated scale · One bowl kept by the sink for the week's food waste

  1. Choose the meal

    30 minutes
    Pick one dinner your household cooks anyway and lock it as the meal you will measure four times.
    • Ask whoever cooks which dinner repeats most often, and write the dish and its usual night at the top of a fresh page.
    • List every item that goes into it on one line each, including oil, salt, tea and anything drunk alongside it.
    • Rule six columns across the page: item, grams, rupees, litres per kilogram, source, litres on plate.
    • Draw the plate as served and label what is on it, or photograph it if a phone is available.
    Write down: The dish name, the date, the number of people served, and one ruled row per ingredient.
    Finished when: The page carries one row per item and a dated sketch or photograph of the served plate.
    Commonest mistake: Choosing a meal you never normally eat because it sounds interesting. Pick the repeated, boring one — you have to cook it three more times.

  2. Weigh the plate

    45 minutes
    Measure the raw mass of every ingredient that ends up on one person's plate.
    • Zero the scale with the empty bowl on it, then weigh each raw ingredient in grams before it goes in the pot.
    • Where there is no scale, measure by level cupfuls, then weigh one cupful once on a shop's scale and write that conversion at the top of the page.
    • Where the pot serves five, divide every figure by five and write the division out longhand so it can be checked.
    • Weigh the served plate too, and record raw and cooked mass separately, because the published figures attach to raw mass.
    Write down: Raw grams per person for every item, the divisor used, and a mark against anything estimated rather than weighed.
    Finished when: Every row carries a raw mass in grams per person and no row says 'about'.
    Commonest mistake: Weighing cooked rice and treating it as raw. Cooked grain has absorbed water and weighs far more than the dry grain it came from — weigh it dry, or write down the conversion you used and its source.

  3. Price the plate

    40 minutes
    Work out what one plate cost in rupees from prices actually paid, not from memory.
    • Collect the receipts, and where there are none walk to the shop and copy the current price per kilogram onto your card.
    • Ask whoever shops where each item was bought and write the shop name beside the price.
    • Do the arithmetic longhand in the margin: price per kilogram divided by one thousand, multiplied by grams on the plate.
    • Add cooking fuel as one line, marked as an estimate, with the reason written beside it.
    Write down: Rupees per item per plate, the shop behind each price, and the total rupees for one plate.
    Finished when: The plate total is one rupee figure and every price traces to a receipt or a shop visit written in the log.
    Commonest mistake: Using a price you remember from last year. Walk to the shop; prices move faster than memory does.

  4. Borrow the figures

    60 minutes
    Obtain a published litres-per-kilogram table on paper and convert your masses to litres by hand.
    • Ask one person with a connection, a college library or a print shop for the Water Footprint Network product figures, or the Our World in Data table of freshwater use per kilogram, printed or copied out.
    • Write the source across the top of the page: the organisation, the table name and the date it was obtained.
    • Copy only the ingredients you need, one per row, with units, and write the source again in the source column of each row.
    • Multiply litres per kilogram by kilograms on the plate longhand, leaving the working visible on the page.
    • Underline the largest single figure and write one line on what that coefficient includes and excludes, in the source's own words.
    Write down: Litres per item, the total litres for one plate, and the source written beside every coefficient.
    Finished when: You can name the item carrying the biggest share of the litres and point to the printed line the figure came from.
    Commonest mistake: Copying a number from somebody's memory or a conversation. If it has no printed source you can show, it does not go in the table.

  5. Weigh the waste

    45 minutes spread over seven days
    Measure the food this household throws away over one week and attach its full footprint to it.
    • Keep one bowl by the sink for seven days; after every meal scrape uneaten food into it and weigh it before it goes in the bin.
    • Weigh anything thrown out uncooked from the fridge as well, item by item, and write the reason it was thrown.
    • Apply the same borrowed coefficient to the wasted mass, because the water was already spent before the food was binned.
    • Rule two more lines at the foot of the page: grams wasted this week, litres thrown away this week.
    Write down: Grams wasted each day for seven days, the reason for each, and the week's litres-wasted total.
    Finished when: Seven daily figures exist, including the zeros, and the weekly litres total sits at the foot of the page.
    Commonest mistake: Skipping the day nothing was wasted. A zero is a measurement; a blank is a hole in the week.

  6. Name the cost

    50 minutes
    Finish the costed problem statement on one page and choose the single change you will make.
    • Write four lines: whose problem this is, litres per plate, rupees per plate, and litres and rupees per year at this household's real frequency.
    • Draw the litres-per-item bar chart on squared paper, largest bar first, with the scale stated and the finding as the title.
    • List three possible changes — swap an ingredient, cut a portion, change where an item is bought, stop one form of waste — with the litres each would save.
    • Choose one and write: 'I will change X to Y for three weeks and expect litres per plate to fall from A to B.'
    • Read the page aloud to whoever cooks and have them sign and date it if they agree to the change.
    Write down: The one-page costed problem statement, the three candidates with predicted savings, and the chosen change as one testable sentence.
    Finished when: Somebody who was not there reads the page once and repeats your litres number back correctly.
    Commonest mistake: Choosing the change that saves most on paper but nobody at home will accept. A change abandoned in week one measures nothing — choose the one that survives.

  7. Agree the rules

    40 minutes
    Write the protocol that keeps the after-measurement identical to the before-measurement.
    • Write what stays fixed: same dish, same scale, same number of people, same shops, same weighing point in the cooking.
    • Write what is allowed to move: only the one thing you named in step six.
    • Rule three blank labelled rows for weeks one, two and three before any data exists, and write the three dates beside them.
    • Write your prediction on the page, date it, and have one person witness it with their signature.
    Write down: The protocol as a numbered list, the three dates, and the witnessed, dated prediction.
    Finished when: The page holds empty labelled rows waiting for three weeks and a signed prediction that predates the data.
    Commonest mistake: Deciding the measurement rules after seeing week one. Anything rewritten once data exists goes in the failure log with the date.

  8. Measure week one

    45 minutes
    Cook the meal with the change in place and measure exactly the quantities you measured before.
    • Weigh every raw item again in grams per person, using the same scale and the same divisor.
    • Write down the prices paid this week rather than copying the Act 1 prices down the page.
    • Use the same borrowed coefficient table — do not change source in the middle of an experiment.
    • Weigh this meal's waste into the same bowl and add it to the running count.
    • Write what went wrong: a substitute ingredient, an extra guest, a forgotten weighing.
    Write down: The week one row complete — grams, rupees, litres, waste — plus a dated failure entry.
    Finished when: Week one carries every column the baseline had, and the failure log holds at least one honest entry.
    Commonest mistake: Crossing out the row for the ingredient you swapped away instead of writing zero. Write the zero; the comparison depends on the same rows existing in both periods.

  9. Weeks two and three

    60 minutes across two weeks
    Repeat the identical measurement twice more and compare all three weeks against the baseline.
    • Cook and measure on the two booked dates, changing nothing except what the protocol allows.
    • Add the three after-weeks and divide by three, longhand, to get the mean litres per plate.
    • Draw four bars on squared paper to one stated scale: baseline, week one, week two, week three.
    • List every confounder you can name: guests, a price rise, an ingredient out of stock, a different cook, a different appetite.
    • Write the change as a number and as a percentage, and say plainly whether three measurements is enough to be sure.
    Write down: The four-bar chart, the mean after-figure, the difference in litres and in rupees per year, and the confounder list.
    Finished when: You can state the before number, the after number, and at least two reasons the difference might not be your doing.
    Commonest mistake: Reporting the best of the three weeks. Report all three, including the week that went backwards — a well-measured failure outscores an unmeasured success.

  10. Share and reflect

    60 minutes
    Publish the finding, defend it to real people, and record what the household will keep.
    • Deliver the defence out loud in under three minutes to three people who sign and date the page, or record it on a borrowed phone.
    • Read the one-page explainer to three people who eat this meal and write down what each of them said.
    • Send or hand the chart to the expert you interviewed with one question: what would you have measured that I did not.
    • Ask the household in front of a witness whether the change stays and why, and write the answer down word for word.
    • Complete the relations ledger with ten names, roles, dates and what each person replied.
    Write down: The defence, signed and dated by its witnesses, the one-page explainer, and the relations ledger holding ten relationships.
    Finished when: Ten relationships are logged with dates and replies, and the household has said on record whether the change stays.
    Commonest mistake: Calling it a success because the household said they liked it. The metric is litres and rupees — report those first and opinions second.

What the student hands in

Nine pieces. Together they are the folder a parent can sit down and read.

1. Question cardOne card naming the dish, the household and the number of eaters, and the question: how many litres and rupees stand behind one plate of this, and which item carries most.
2. Expert interview packFive written questions for an agronomist or irrigation engineer, your plate figures attached as one page, the date and channel of the request, and the reply recorded word for word.
3. Evidence logEvery weighing in grams with its date, every price with the shop it came from, and every litres-per-kilogram coefficient with the exact source line beside it. Nothing unsourced survives here.
4. Failure logThe weighings you missed, the ingredient substituted mid-experiment, the week the swap was abandoned, the guest who doubled the pot, and what each of them did to the comparison, all dated.
5. The buildThe measuring set-up itself — scale, waste bowl, ruled table or sheet — together with the four-bar comparison chart of litres per plate, baseline against the three after-weeks, on one axis.
6. One-page explainerOne page a neighbour reads in ninety seconds: the dish, the litres, the rupees per year, the one change, the three-week result, and what this figure cannot tell anybody.
7. Identity cardA name and a one-line promise for the measurement, so the household can refer to it by name, plus the single sentence you want repeated at somebody else's dinner table.
8. Relations ledgerTen names with dates and replies: one agronomist, three people who eat this meal, three peers who checked your arithmetic, and three people you sent the chart to who answered.
9. Defence videoUnder three minutes on camera: the plate, the litres figure, the source of every coefficient, the one change, the three-week result, and the limits you accept without argument.

The expert they have to find

Ten logged relationships are required before this project can be marked. One of them is an expert, and this is who.

An agronomist, irrigation engineer or agricultural extension officer — somebody who decides how much water a crop actually gets. A rice mill manager or a dairy farm manager works equally well.

How to find one

Ring the district agriculture extension office listed on the provincial agriculture department site. Agricultural university departments publish staff emails. Search LinkedIn for 'agronomist' plus your city. Failing all three, the manager of a rice mill, a dairy or a vegetable wholesale market will know the water figures for their own crop.

What to say

Hello, my name is [name]. I have weighed one dinner my family ate and worked out the litres of water behind it from published per-kilogram figures. One of my numbers looks wrong to me. Could you spare fifteen minutes on the phone this week to tell me which one? I will send my five questions first.

What to ask

  • For the crop you know best, how many litres of water reach one kilogram at the farm gate, and how do you know that figure?
  • Published water footprints are national averages. How far off would that average be for a field in this district, and in which direction?
  • Which of the ingredients on my plate would you say is the most water-expensive, before I show you my numbers?
  • When a farmer changes one practice, how long before the change shows up in water use, and how is it measured?
  • If a buyer asked you to prove a shipment's water footprint tomorrow, what evidence would you actually send them?

The defence

Eight of the twenty marks. A student who cannot answer these has not finished, however good the artefact is.

  • Would this drop in litres have happened anyway without your change, and how do you know?
  • Your litres-per-kilogram figures are averages taken somewhere else. What would the figure be for the field that actually grew your rice, and how would you find that out?
  • You measured three weeks. Convince me three is enough, and tell me what a fourth week would most likely have shown.
  • If the household goes back to the old ingredient next month, what was this project worth, in litres and in rupees?

How far a student can take it

starterYou weigh one plate, price it from real receipts, look up every litres-per-kilogram figure with its source written beside it, and put your questions to one stranger who works with crops.
practitionerYou choose which meal to measure and defend the choice, cite every borrowed figure to its page, and produce one chart a stranger reads correctly without you explaining the axes.
researcherYou write the protocol before the first weighing, justify three after-weeks rather than one, and quantify the error your scale, your per-person divisor and globally averaged coefficients introduce.
contributorYou set your plate figure against a published water-footprint study, defend your method to an agronomist who disagrees, and publish your raw weighings and every source openly so others can recompute it.

If you want to go further

Measure the same dish cooked in a second household and set the two plates side by side, item by item, on one chart.

When it goes wrong

  • If nobody replies to your interview requests - then stop writing and go to the vegetable wholesale market at opening time and ask one trader two questions while they work.
  • If your before and after look the same - then report that as the finding, check first whether the change was actually kept on every one of the twenty-one days, and write what you find in the failure log.
  • If you cannot weigh an item - then measure it by level cupfuls, weigh one cupful once on a shop's scale, write that conversion at the top of the page, and mark the row as estimated.
  • If you run out of time - then shorten the after-period to two weeks rather than dropping the baseline, and state the shortened period on the chart itself.

Before you start

Safety and consent.
  • Measure a meal the household was cooking anyway. Do not cook anything extra for this project and do not use the stove, hot oil or a sharp knife for it — every weighing is of raw, cold ingredients before they go in the pot.
  • Nobody's plate gets smaller for the sake of the number. Weigh what is served, and if a portion or an ingredient changes in Act 2, agree it first with the person who has to eat it.
  • Weigh raw meat, fish and eggs in a bowl or on a plate, never directly on the scale surface. Wash your hands and the bowl afterwards, before touching the notebook or the phone.
  • Handle only your own household's food waste, in a bowl kept for the purpose, and wash your hands after every weighing. Never open a neighbour's bin, a shop's bin or a street container.

Run this with a class

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