Lesson Plan

Lesson Plan

We encourage educators, teachers, and parents to use our lesson plan to provide students a fun way to learn about food waste. There are also lessons about composting, recycling, & waste water, to provide full exposure about envirvonmental sustainability. Enjoy! –Waste Watchers



  1. Landfills and Greenhouse Gas Emissions


  1. Background Information: So your trash hits the landfill. Does it just sit there? No, it slowly breaks down. So what happens to it? It is broken down by bacteria. Bacteria, like us, have to resperate. In doing so, they excrete waste as Green House Gases. Here’s what happens in a landfill:


  1. Your trash gets dumped in a landfill along with a lot of other trash. There are air pockets between the garbage that have oxygen stored in them. Like us, bacteria will use oxygen to break down their food. Breaking down food through the use of oxygen is known as aerobic respiration. So they take in oxygen and release carbon dioxide.
    1. Reminder: Carbon Dioxide is a greenhouse gas. What this means to be a greenhouse gas is that the gas is very good at trapping heat. The more heat that gases in our atmosphere traps, the warmer Earth gets, contributing to Global Warming.


  1. This will go on until the bacteria run out of oxygen. At that point, bacteria will break down organic compounds through another process that does not require oxygen, called anaerobic respiration. Through this process, bacteria will produce alcohols, like ethanol, in addition to carbon dioxide. What you need to know about these chemicals is that it makes the landfill environment highly acidic. These acids will dissolve nutrients and make Nitrogen and Phosphorous available for organisms to use. Now bacteria are often limited by the absence of these nutrients. If you need Nitrogen to grow and there is none, then you can’t grow. By increasing the amounts of these nutrients, the growth of new types of bacteria is encouraged.


  1. Eventually, you’ll end up with a type of bacteria that consumes these acids and will make their environment more neutral. Now we have a neutral environment with a good amount of Nitrogen and Phosphorous. What happens next is that methane producing bacteria establish themselves and suddenly, the landfill starts pumping out methane in addition to carbon dioxide.


  1. So what’s wrong with methane?

We talked about how Carbon Dioxide is very good at catching heat. Methane has the potential to catch about 30 times more heat than methane can.


  1. Activity: Heat Catch – The purpose of this activity is to demonstrate how certain greenhouse gases are more effective at trapping heat than others.

Methane has the ability to trap more heat than carbon dioxide because there exists a higher concentration of methane per unit area than carbon dioxide. To simulate this, students will use their hands to catch balls.

Call up one student who will act at carbon dioxide. You will toss tennis balls to them and then using one hand, the student has to catch as many as they can. Throw 5 or 6.


Then let the student use both hands. This demonstrates the ability of methane to catch more heat per unit area than carbon dioxide. Throw the same number of balls and compare how many were caught.


  1. Discussion:
  2. Methane is the second most abundant greenhouse gas after Carbon Dioxide. If our emissions keep increasing, what do you think this means for the Earth?


  1. What do you think we can do to reduce the amount of greenhouse gases in our atmosphere?



  1. Significance: Methane has a relatively short lifespan of 12 years. That means that if we act now, we will be able to see the effects within our lifetimes. So let’s talk about what composting can do for our environment.


Source: Waste and Landfill Fundamentals by Timothy G. Townsend, Jon Powell, Pradeep Jain, Qiyong Xu, Thabet Tolaymat, and Debra Reinhart.                                                                      For more information, visit https://www.atsdr.cdc.gov/hac/landfill/pdfs/landfill_2001_ch2mod.pdf


  1. Composting


  1. What is Composting:

Composting transforms biodegradable material into rich soil. There are a lot of different ways to do it, but moral of the story is that you want to do it, you have to add oxygen to the soil. At home, this can be done by using red worms or by manually turning the soil. On an industrial scale, air is mechanically blown into compost piles or piles are turn using grander equipment. Turning your compost introduces oxygen back into the system, which will help to reduce the amount of methane that is produced. Keep in mind that Carbon Dioxide will still be produced by bacteria, but overall, the process has a significantly lower environmental impact than just dumping our trash in a landfill.


  1. Identifying Compostables:

Anything that is biodegradable can be composted, but typically the main things you want to be composting are food items and easily broken down things like pizza boxes and things of those nature.






  1. Composting and Making Your Own Compost Pile:

Things needed:

  • Mason jars
  • Green stuff (grass clippings, fruit and veggie scraps, tea bags, veggie leftovers)
  • Brown stuff (dead leaves, old flowers, hay, saw dust)
  • Air (pop holes in lid),
  • Water (add small amounts of water to compost bin but not too much)
  • Soil ( use some garden soil to introduce the right bacteria), dirt
  • Wash, Rinse, Repeat
  • Wood shavings or twigs (optional)


  1. Construct a bin for your compost.  While it is possible to compost food waste without the use of a bin, a bin keeps everything in one area so that it is easier to manage the composting process.  The use of a bin will also deter animals from trying to eat any food scraps you put on your compost pile. Some designs of bins even assist in maintaining a good moisture and temperature in the compost.  The smallest you want to have your compost pile, if you want to make an efficient one, is one cubic meter. A larger pile will assist in the volume of food you can add to it, but a smaller scale pile will work just as good if you aren’t producing enough food waste to constitute a bigger pile.
  2. Fill your bin with a balanced mixture in order to get the best results. Use green stuff that is high in nitrogen to assist with heating your compost. Ideal green stuff includes young weeds (before they develop seeds), comfrey leaves, yarrow, manure, grass cuttings, etc. Other green items that work well includes fruit and veggie scraps, coffee grounds, and tea leaves. Use brown stuff that is high in carbon to serve as the bulk for your compost. Brown stuff includes leaves, dead plants, sawdust, old flowers, and hay. Other items that can be composted includes paper products, egg shells, and torn up cotton clothing. You’ll also need air, water, and a warm temperature for the best results. Air is required to compost aerobically; anaerobic composting uses different bacteria, smells sour, and attracts flies. So be sure to turn your compost pile when it needs air. Your compost pile should also be moist, but if it is too wet it might not get enough air. Also, the compost pile should feel warm to the touch as it is an indication of the microbial activity in the decomposition process. You can also add soil or starter compost between layers to help the process get started.
  3. Layer or mix the different materials in your bin so they come into contact with each other and so that you avoid clumps in your compost.  Avoid compacting materials, specifically the green ones, together since they can become anaerobic really quick. You should start your compost with a layer of brown material such as leaves to keep enough air at the bottom of the pile.  Mix in three parts brown to one part green to half brown half green depending on the things you put in the compost pile. Add water if your pile gets too dry when you’re making it.
  4. Actively turn your pile about once every week or two.  Have a clear area next to the pile so that, with the use of a pitchfork, you can move the pile to the clear area then move it back to its original spot when it needs to be flipped again.  Actively mixing allows air to get into the compost keeping the process aerobic instead of anaerobic. Anaerobic decomposition will smell bad (like vinegar) and it takes way longer to decompose waste anaerobically.  Turning the pile assists in encouraging growth of the correct bacteria and makes for a nice, sweet-smelling pile that will decompose faster. Try to move the stuff on the inside of the pile to the outside and from the top to the bottom of the pile.  Break up any clumps you see, and water if the pile appears too dry. If the pile seems too wet, add some brown materials. If you are still adding new matter to the pile, add the new stuff in with the old stuff well.
  5. Add slow rotting items as preferred such as: branches, twigs, hedge clippings, ash, and wood shavings. These items will take longer to break down, so you may want to compost them separately. Shred heavier materials if possible for faster decomposition.
  6. Never compost the following items: meat scraps, bones, fish, plastic, oil, fat, human or pet feces, diseased plants, diapers, glossy papers, coal ash, or cat litter. These items should be disposed of in the garbage. These items should not be composted for reasons of health, hygiene, and inability to decompose.
  7. Harvest the compost. If everything goes to plan, there should be a nutrient-rich layer of soil at the bottom that you can use. Remove that layer and add it to your garden or whichever plants you need soil for.  Use a sieve to get rid of any large chunks you can’t remove. Also make sure that the compost has finished decomposing, because if you use it too soon, it will rob the soil of nitrogen as it continues to break down.  If you aren’t certain whether it has finished composting or not, leave it for a few more weeks or add it to your garden bed and let it sit for some time before introducing plants. It’s totally fine to flip compost for a while to break down bark or wood. Typically, when pitchforking the pile, the pitchfork will move wood to the top.

Source: The City of Alexandria Virginia’s description of Yard Waste Recycling.       For more information, visit: https://www.alexandriava.gov/YardWaste

  • Benefits of Composting


  1. Composting improves soil structure:

Good soil tends to clump together, forming irregularly sized particles, called aggregates. This opens channels for water to drain through, air to circulate in, and plant roots to grow in. However, sandy and clay soils have poor structure. They do not clump together the way a richer soil would, resulting in poorer drainage and nutrient circulation. Compost, in contrast, adds organic matter to the soil that helps hold onto water and circulates nutrients in the soil.


  1. Activity: Soil Crawl- the purpose of this exercise is to demonstrate how soil structure impacts the movement of water through soil systems.

Students in this exercise will mimic the two types of soil. First, they will mimic sandy soil. To do this, students will stand with outstretched arms. One student is designated as a water molecule and must try to navigate through the open spaces between students without going under their arms. Then, students emulate a soil with compost added to it. Students turn their arms toward another student that is next to them. Again, the water molecule must try and move through them. It should be far easier to do in the soil with compost added.


  1. Discussion:
  2. Why is compost important for improving plant growth based on what we did?
  3. What would happen if you were to apply Nitrogen or Phosphorous based fertilizers to a soil with poor drainage?
  • Runoff into water bodies causing algal blooms. When these algae die, there will be bacterial growth to decompose them. These bacteria will use up all available oxygen, creating a dead zone where aquatic life cannot exist.
  1. Improves Nutrient Retention

Many of the nutrients that exist in the soil are positively charged. In contrast, clays and organic matter tend to hold extra electrons, making them negatively charged. These opposite charges act like opposite sides of a magnet, causing for positively charged nutrients to stick to negatively charged electrons. Therefore, as the amount of organic matter in the soil increases, the soil becomes better at holding on to nutrients that are added. Ultimately, this benefits plants. Soils without organic matter, however, are unable to hold onto nutrients. Should fertilizers be added to these types of soils, most of the nutrients will be removed through runoff, since the soil still has no way of making the nutrients stick around. Adding compost to soil adds the negatively charged particles necessary to hold onto nutrients and to better support plant life.


Source: Planet Natural Research Center on Compost and Soil.

For more information, visit: https://www.planetnatural.com/composting-101/soil-science/compost-soil/



  1. Waste Water


  1. Background Information

The average European and North American throws away almost 220 pounds of food annually. Worldwide, this equates to 1.3 billion tons of food that head to our landfills. From here on out, we’re going to talk about the problems associated with sending this much food to our landfills and what we can do to minimize our food waste.

What if I told you that you eat 3,496 Liters of water per day? First there is the water that we use in our homes every day for cooking, cleaning, bathing, and drinking. We use about 173 Liters of water daily for these domestic purposes. Then there is the water that we use, but can’t see. It takes water to create products, like for growing the cotton plants used to make your shirt. We use about 167 Liters daily to make industrial products. Then there is the water that is needed to produce our food. We are going to show how easy it is to hit 3,496 Liters. With the 1.3 billion tons of food that hit our landfills, we waste 45 trillion gallons of water. First, we’re going to talk about the relationship between the food we eat and water.

  1. Activity: Family Dinner– The purpose of this game is to demonstrate how much water goes into the food we eat.

Break students up into families of 4. Items from different food groups will be listed at the front of the room and groups will have to make a meal plan for their family with one food from each food group. After this is done, reveal how much water it took to make each food. Have students sum up their totals, with the objective of staying under 3,496 Liters, or 923 Gallons.

See list of food items in the Lesson Appendix A


  1. Significance: Look at the food you took and realize how many things that you put on your actual plate that didn’t make your list. Now realize that most Americans will throw away about 40% of the food they buy. About one quarter of the water that we use to irrigate our crops is lost as food waste. As we look at places like California, who has struggled to find enough water to tend their agriculture, realize that when we take food that we don’t eat, we are throwing away water.


  1. Discussion:
  2. Why does it require so much water to produce livestock as opposed to fruits and vegetables?
  • Take beef, as an example. Beef is a living animal and has to be supported for 3 years before being slaughtered. It takes about 800,000 pounds of water to produce the food that will feed the cow and then the cow itself will drink 6,000 Gallons worth of water. Living animals have additional water requirements that plants do not have.
  1. What are things that you can do to minimize your water footprint?


Source: Water Footprint Network, Virtual Water by Tony Allan.

For more information, visit: http://thewaterweeat.com



  1. Landfill Use


  1. Background: Alright, so after you throw away your food, it has to actually go somewhere. Produced but uneaten food occupies 1.4 billion hectares of land, approximately one third of Earth’s available agricultural land. Apples take about one month to decompose in a landfill. Let’s look at what happens:


  1. Activity: Garbage Dump – The purpose of this activity is to demonstrate how quickly landfill space can be filled with an expanding population.

Students are broken up into groups of 4. Students count off and each take a number. Each group receives two squares: a green farm and a green farm that when flipped reveals a landfill. Each landfill has a number (11,12,13,14,15,16,17) which refers to how many chips can be placed in it. Groups have four cups with red (week 1), blue (week 2), yellow (week 3) and orange (week 4) chips in cups at their desks. Each week, living students will each place a chip in their landfill. Chips that have been on the board for four weeks clear.

  • Week 1: Only student 1 is alive. They take a chip from their farm and need a place to put it. They flip over their landfill.
  • Week 5: Remove red chips off of the board. Student 2 is now alive as well. Both put a red chip on the board.
  • Week 9: Student 3 is now alive as well.
  • When the first landfill fills, students stop. The group buys landfill space from another group (toss them candy as a reward).
  • Week 13: Student 4 is now alive. The game continues until all landfills are filled.


  1. Discussion:
  2. Okay, so what just happened? Why did it happen?
  3. So what happens now? The problem you guys are having right now is the same problem that England is currently experiencing, who is projected to run out of available landfill space in 2018. What can we do about it?
    1. Incineration: Here are the downsides to that: Burning our trash will release greenhouse gases into the atmosphere. Additionally, incinerators will have to be big to make this functional, which means transporting trash to it.
    2. Compost it. Composting speeds up the decomposition process because it provides optimum conditions to break down organic matter. Faster turnaround time means more available space.
    3. Buy less and throw away less.


Source: Food Wastage Footprint Impacts on Natural Resources Summary Report by the Natural Resources Management and Environment Department.

For more information, visit: http://www.fao.org/docrep/018/i3347e/i3347e.pdf



  1. Recycling


  1. Background Information: Here is an overview of what can and cannot be recycled.
    1. Almost all metals go into recycling, including Aluminum cans, bakeware, and tine cans.
    2. Paper and cardboard products can be recycled, such as corrugated cardboard and newspaper.
    3. Glass bottles and jars are set to be recycled once you rinse them out and discard their caps. Don’t worry about labels on bottles as they will burn off at the plant.
    4. For plastic, the basic idea to keep in mind is that if the bottle of the bottle has a neck that’s smaller than the body and has “alor2” symbol on the bottom, nearly every program will accept it.



  1. Activity: Trash Can Free Throw – The purpose of this activity is to have students learn the rules of recycling.

Method: Students are divided into 2-4 groups depending on the size of the class. Each group receives a stack of paper, each with a different trash item on it. When it’s a group’s turn to go, they read out the trash item. They’ll have 15 seconds to discuss with themselves whether or not the item can be recycled at their curbside. They will them crumple up the paper, and call out their answer. If they are correct, they get a point and get to make a free throw into the bin. If they make it into the bin, they get an extra point. If the students make an incorrect guess, they throw their ball to another team and that team gets to try and steal the points. The team with the most points at the end is the winner.


See the list of recyclables in the Lesson Appendix B


  1. Discussion
    1. Okay, so you order a bottle of shampoo on Amazon. Tell me what you do with your garbage.
    2. Where are recycling containers located here on campus?
    3. Do you feel compelled to recycle on a daily basis? Why or why not? What could you guys do to care more about it?


Source: “What Can I Recycle” by Waste Management.

For more information, visit: http://www.wm.com/thinkgreen/what-can-i-recycle.jsp



  • Expiration Dates


  1. Background:

“Use by” and “Best by” dates emerged in the 1970’s as Americans started producing less of their own food but still wanted to know about how it was made. The dates you see on your food don’t all reflect when it is no longer safe to eat it, they just reflect when your food is at the peak of its freshness.

“Sell By” is meant as a tool for retailers so that they know when they need to sell the item so the consumer still has time to use it.


See list of food items in the Lesson Appendix C


  1. Activity: To Eat or Not to Eat – The purpose of this activity is to have students recognize that foods can be eaten past the printed date.

Students divide into teams. Each time is given two signs to raise, one that says yes and one that says no. A food item and an expiration date are read, teams are given twenty seconds to deliberate and then raise a sign. For each correct answer, teams are given one point. The team with the most points by the end of the game wins.


  1. Discussion:
    1. Have you guys ever looked at a use by date on a food that was clearly still fine to eat but threw it away because of the date? Would you now feel comfortable eating it? Why or why not?



Source: “About Eat by Date- How Long Does Food Last” by EatByDate.

For more information, visit: http://www.eatbydate.com




  • Lesson Appendix


  1. Waste Water Game Information
  2. Carbs
  3. Pasta — 222 gal/lb
  4. Rice – 299 gal/lb
  5. Bread — 193 gal/lb
  6. Potatoes — 34 gal/lb
  7. Oats — 290 gal/lb
  8. Corn — 146 gal/lb
  9. Fruit
  10. Orange — 61 gal/lb
  11. Grapefruit — 77 gal/lb
  12. Bananas — 100 gal/lb
  13. Strawberries — 50 gal/lb
  14. Raisin — 292 gal/lb
  15. Vegetables
  16. Broccoli — 34 gal/lb
  17. Tomato — 26 gal/lb
  18. Asparagus — 258 gal/lb
  19. Lettuce — 28 gal/lb
  20. Cucumber — 98 gal/lb
  21. Dairy
  22. Milk — 46 gallons/8 fluid oz
  23. Cheese — 56 gallons/oz
  24. Plain Yogurt — 88 gal/cup
  25. Proteins
    1. Chicken — 548 gal/lb
    2. Beef — 1,847 gal/lb
    3. Pork — 718 gal/lb
    4. Tofu — 302 gal/lb
    5. Lentils — 704 gal/lb



  1. Recycling Game Information
  2. Plastic yogurt container with a spoonful of yogurt left in it—
    Yes, it can be recycled! The heat at which glass, metal, and plastic recycling processes run is enough to remove food residue as well as the labels in containers. With that said, the cleaner your container is, the more it is worth, so the greater the profit the city can make on your recycling to further fund the program. You may want to keep food residue off as well for the health safety of recycling employees as food will mold.

    2. Pizza Box with grease stain—
    No. When paper is recycled, it s mixed with water to form slurry. The oil and fat from food don’t mix with water, and so rise to the top of the mixture with the paper pulp, forming lower quality paper.

  3. Blue glass—
    Yes, it can be. However, different colored glasses are recycled differently as their uses and recycling processes differ. Combining wrong colors and ruin batches of recycling, so check with your local program on the proper protocol.

    4. Ceramics –
    No. They don’t melt like glass and they aren’t organic, so they can’t be composted. They go to landfills.

    5.         Car Batteries –
    No, they cannot be recycled on your curbside. However, they can still be recycled. Generally, automotive retailers will take them back.

    6.         Compact Fluorescent Bulbs –
    Yes! However, they contain small amounts of mercury in them, so it is recommended that you bring them to a qualified recycler rather than just throwing them in a curbside recycling bin. Most light bulbs actually can be recycled in manner similar to this!

    7.         Window Glass –
    No. While it can be melted down, it melts at a different temperature than bottle glass. As a result, recycling plants have driven their focus hard on recycling bottles, not window glass, so it is recommended that window glass just be thrown away.

  4. Wire hangers –
    No, most recycling places are not set up to handle wire.
  5. Styrofoam –
    No, most recycling plants will not accept it.

    10. Plastic Bags –
    No. It isn’t cost effective for workers to check what is inside your plastic bag, so they get tossed. You can, however, bring them back to supermarkets for reuse.

    12.       Batteries:
    No, they cannot be recycled on your curbside. However, stores like Office Depot will actually recycle reusable batteries for you!

    13.       Brita Water Filters:
    No. However, Whole Foods will collect and recycle them.

    14.       Cosmetic Packaging:
    No. However, certain cosmetic stores will recycle them. Lush will accept old packaging and if you bring back the packaging from 6 of their products, MAC will give you a free lipstick!

    15.       Wet Paper:
    No. Wet paper fibers are less valuable, so plants will not recycle them.

    16.       Plastic Bottle Caps:
    No. Plastic bottle caps are not overly valuable on the market, so plants will not recycle them.

    17.       Juice Boxes:
    No. Check your juice box to see if it was specially rendered for recycling. Otherwise, there is too much plastic coating on the cardboard to be recycled.

  6. Expiration Date Information:
  7. Unopened almond milk, 1 month past the printed date
    1. Yes! All unopened milk alternatives are good for a month past the date printed. Once opened, all opened milk alternatives last 5-7 days past the date printed.


  1. Eggs three weeks past the sell by date.
    1. Yes! Eggs are good for 3-4 weeks after the date.


  1. Opened milk, one week past its sell by date.
    1. Yes! Opened milk can last 5-7 days past the date printed.


  1. Unopened ice cream, 6 months after the date printed.
    1. But it does last 2-3 months after the date in the freezer.


  1. Unopened Coca-Cola bottle, one year past the date.
    1. No, but it can be good up to 9 months after the date printed.


  1. Unopened Gatorade, 6 months after the date.
    1. Yes! They can be good for up to 9 months.



  1. Canned fruit on your shelf that is one year past its expiration date.
    1. Yes! Canned fruit can last one to two years past its printed date.


  1. Opened frozen fruit, one year past its expiration date.
    1. No, but it can last 8-10 months.


  1. Opened cereal, 5 months past its expiration date.
    1. Yes! Opened cereal can last 4-6 months in the pantry. Unopened cereal can last 6-8


  1. Instant oatmeal three years after the printed date.
    1. No, but it can last 1-2 years.


  1. Pop Tarts 8 months after the printed date.
    1. Yes! They are good for approximately 6 – 12 months after the date printed.


  1. Raw white rice, 4 years after the printed date.
    1. Yes! It is good for 3-5 years.


  1. Raw brown rice, 4 years after the printed date.
    1. No, it is good for 6-8 months.


  1. Dry pasta one year after the printed date.
    1. Yes! It is good for 1-2 years.
  2. A refrigerated and opened package of ham, one week past the printed date.
    1. Yes! It is good for 7 -10 days.
  3. Refrigerated salmon, one week past the printed date.
    1. No, but it is good for another 1-2 days.
  4. Refrigerated tofu, one week past the printed date.
    1. No, but it is good for 3-5 days.
  5. Opened peanut butter in your pantry, 6 months past the printed date.
    1. No, however, opened peanut butter in your fridge is good for 6-8 months. In your pantry, opened peanut butter lasts 3-4 months.
  6. Dried beans, 4 years after the expiration date.
    1. Yes, they can last indefinitely.
  7. Unopened spam, 4 years after the expiration date.
    1. Yes, it can last for 2-5 years.