Click here to view the entire version of VRG’s new lesson plan for kids grades 5-8 about water usage.
by Jeanne Yacoubou, MS © The Vegetarian Resource Group
Purposes:
- To calculate total daily water consumption and average daily water consumption including both direct and indirect uses.
- To compare and contrast students’ water use.
- To graphically represent data in tables and histograms.
- To correlate water use and dietary choices.
Objectives: As a result of this lesson’s activities, students will be able to:
- Identify direct and indirect ways that people consume water on a daily basis.
- Calculate daily averages of personal water use based on established reference values.
- Display data in tabular and histographic form.
- Make cross-comparisons concerning water usage in terms of dietary choices.
- Propose ways to mitigate water consumption on personal, national, and global levels.
Lesson Background:
Teachers may look at the United Nations’ 2006 report titled
Livestock’s Long Shadow available at http://www.fao.org/docrep/010/a0701e/a0701e00.htm. Chapter IV deals with water pollution due to animal agriculture. Both national and global issues are discussed. The major conclusion of this Report is that livestock production is a leading source of environmental damage including climate change; water and air pollution; land degradation; and loss of biodiversity. The Report suggests that a human diet that is plant-based would prevent much of the environmental damage caused by animal agriculture, including the feedcrop production associated with it.
Please see the section titled Water Facts (below) for tabular information and other relevant statistics involving direct and indirect personal water use.
Procedure:
NOTE: The students need to keep a daily log of their
water usage for approximately seven days. Calculating the daily water use of friends or family members with different dietary preferences (e.g., vegetarian or vegan) for comparison purposes may contribute added insight.
Lesson Step #1: Introduction and Topic Setting
The teacher introduces the subject by role playing a "water waster" by letting the water run in the classroom, cafeteria, and/or bathroom. Teacher leads a general
discussion to determine how much students know about the quantity of water needed to perform common daily activities (e.g., flush a toilet). Showing the EPA table (Table 1 below) of common values may be instructive. Teacher may ask how someone can conserve water in daily living. To lead into the activity, teacher proposes that food choices also can be responsible for water wastage in an indirect way. Showing Tables 2 and 3 (below) will be helpful at this point. Students may conclude that purchasers of these foods are indirectly responsible for the water use and/or pollution.
Lesson Step #2: Activity: Daily Log of Personal Water
Usage and Sample Determination
- Students discuss daily log sheets with teacher and among
themselves. All obvious water uses need to be calculated (toilet flushing, brushing teeth, taking showers, etc.) as well as the not so obvious uses: water used for growing food, preparing food, etc. - Students discuss ways to determine flow rates of showers, toilets, etc. This may be accomplished by looking through
manufacturer materials or websites, contacting manufacturers, or
doing a calculation. Calculations may be done using a watch and
large empty containers. The amount of water collected per minute
may be determined. Students should be advised to standardize the
flow rates used over all the days of data collection or told about
the necessity of recalculating them each time. For cooking, personal quantities may be calculated by dividing the total amount of water used to cook a food item by the number of people eating the meals consumed. Similar calculations would be done for clothes and dish washing. Alternatively, one can estimate the quantity eaten/consumed. - Students determine amount of water collected in a given time
frame from a classroom, bathroom, or kitchen sink as an example
using empty containers and a stopwatch. - At the end of the predetermined data collection time period,
students assemble all data into a class histogram. See sample below.
Lesson Step #3: Culminating activity: Students present to everyone what their average daily use of water was. Students display their histograms. Students summarize conclusions drawn based on questions from the lab sheet
Water Facts:
Table 1. Water Consumed during Daily Activities (data taken from http://www.epa.gov/reg5rcra/wptdiv/p2pages/water.pdf)
| Activity | Water consumed (gallons) |
| Flush toilet | 5-7 |
| Run dishwasher | 15-25 |
| Wash dishes by hand | 20 |
| Water a small lawn | 35 |
| Take a shower | 25-50 |
| Take a bath | 50 |
| Wash a small load in a washing machine | 35 |
| Brush teeth with water running | 2-5 |
U.S. and Global Daily Water Intakes
Chapter Four of Livestock’s Long Shadow cites sources that on average, people consume 30-300 L of water per day for household uses while 3,000 L of water are used to grow their daily food.
David and Marcia Pimentel, authors of Food, Energy, and Society, 3rd ed. (2008), cite sources that Americans average 400 L water/person/day. They point out that in eighty-three other countries, the average daily water use per person is below 100 L. In the U.S., daily freshwater withdrawals of surface and groundwater used mainly for irrigation of crops for humans and livestock are 5,700 L per person. Worldwide, the average daily value of water for food production is 1, 970 L/person.
Table 2.Water Used to Produce Some Common Items
(Note: One liter is approximately the same as one quart. One kilogram is approximately the same as 2.2 lbs.)
| Food Item | Hoekstra & Chapagain (L/kg) |
| Corn | 500 |
| Wheat | 850 |
| Soybeans | 1,900 |
| Rice | 1,600 |
| Cow’s milk | 700 |
| Eggs | 1,500 |
| Beef (feedlot) | 13,000 |
| Pork | 3,900 |
| Poultry | 2,400 |
Note: Values taken from Chapagain A, Hoekstra A (2004) Water Footprints of Nations Volume One: Main Report. Value of Water Research Report Series No.16. Delft (The Netherlands): UNESCO – IHE Institute for Water Education. http://www.waterfootprint.org/Reports/Report16Vol1.pdf
Table 3. Water Used to Produce some Common Items (Data taken from Hoekstra and Chapagain 2004; numbers are rounded off on table children use for activity.)
(Note: One liter (approximately one quart) equals 1,000
milliliters (ml). One pound equals 454 g.)
| Product | Water used (gallons) |
| 1 cup of coffee (125 ml) | 140 |
| 1 glass of milk (200 ml) | 200 |
| 1 slice of bread (30 g) | 40 |
| 1 slice of bread (30 g) with cheese (10 g) | 90 |
| 1 potato (100 g) | 25 |
| 1 bag of potato chips (200 g) | 185 |
| 1 apple (100 g) | 70 |
| 1 glass of apple juice (200 ml) | 190 |
| 1 egg (40 g) | 135 |
| 1 hamburger (150 g) | 2400 |
| Dry pasta (made in Italy;1 kg)* | 1900 |
| Cheese pizza (made in Italy; 725 g)* | 1200 (or 248 L per 150 g = ~¼ pizza) |
| Tomato pizza (made in Italy; 600 g)* | 300 (or 75 L per 150 g = ~¼ pizza) |
Note: Values taken from Chapagain A, Hoekstra A (2004) Water
Footprints of Nations Volume One: Main Report. Value of Water
Research Report Series No.16. Delft (The Netherlands): UNESCO –
IHE Institute for Water Education. http://www.waterfootprint.org/Reports/Report16Vol1.pdf
Asterisked values taken from Aldaya M, Hoekstra A. (2009) The
Water Needed to Have Italians Eat Pasta and Pizza. Value of Water
Research Report Series No.36. Delft (The Netherlands): UNESCO –
IHE Institute for Water Education. http://www.waterfootprint.org/Reports/Report36-WaterFootprint-Pasta-Pizza.pdf
Click here to see the complete lesson plan.