Ecosystems and the Food Web

By: Sherezada Acosta

I- Intro

(for older kids only)

Activity #1:

Objective: begin class with something fun to get them more motivated

*Get everyone in a really tight circle where everyone is facing the otherís back

*Slowly get them all to sit down at the same time on each otherís lap

-See how we all depend on each other in order to be able to sit down?

-Here we depend on each others legs and the tight circle to sit down, but today we will learn of a different type of dependence...


-any one ever heard of the word ECOSYSTEM?

-who can spell it for me? (help them write the word on the board or piece of paper)

*use next activity to explain it well


II- What is an ecosystem?

Activity #2 : Yarn Web

Objective: learn how everything in an ecosystem is connected

-Immediately have everyone get up and form a circle

-Explain the rules:

-gently toss the ball of yarn to someone across or around you while holding the end of the yarn

-Keep tossing to someone who hasnít gotten it yet, until everyone is holding a piece of yarn

**Make them do it as quickly as possible to make it more fun**

-Explain how you will begin tugging and everyone has to stay really still until they feel the tug so they can tug the next person.


-Are we all connected? Ö YES!

-What else is connected as we are?

-are the chairs? NO! (say a few others things that will get them to shout NO)

-Hint at the biosphere (maybe show them the bottles they made on the 1st class)

-Remind them how everything is connected in the biosphere

- Ask again what is an ecosystem, while they are holding on to the yarn

Formal definition:

Ecosystem = the combination of all the living organisms, the physical environment and all their interrelationships in a particular unit of space. Composed of the abiotic (climate, soil, water, sunlight...) And biotic (animals, plants,...) constitue nts

-What happens if we cut one part of the yarn? (cut it)

(have them tug and realize that it wonít go all around)

*the perfect system is broken*

*in the same way if a part of the ecosystem is destroyed or damaged the whole system will suffer




III -How is it all connected?

-Is an ecosystem connected by yarn as we were? (NO!)

-What are the 2 things an ecosystem is connected by?

-The flow of the Sunís energy (remind them of previous class on energy and its importance for life)

-The nutrient cycle (remind kids how the worm poop gave nutrients to the plants)

Thought Activity: car analogy

- A life (plants, animal and humans) is like a car

- What do cars need to run?

-Fuel and all of its Parts

(w/o them the car doesnít run)

Nutrients = form all the parts of the car

Sunís energy = fuel

Problem: Last time we talked of the importance of the Sunís energy for life and today I am saying it again, but I wonderÖ. can any of you actually get energy just from standing outside?

Scenario: itís really hot, you are really tired from running around and playing ball, can you just stand under Sunlight and have energy again?Ö NO!

Explanation: Ah! The reason is because we canít absorb this important energy, but Nature is really smart and it came up with one type of organism that can. Any guesses? Ö. Plants! (hint at it if you nee d to with the babies)

-Green plants take the light energy and convert it to chemical energy (from Joseís lesson, but with babies probably donít want to use that word) which is something we can all absorb. The plants are the ones that turn this energy from the Sunlight into the fuel that you and I need to be alive.


IV- What are the terms used?

-If plants PRODUCE the fuel what do scientists call them? Ö. (ask these questions to the babies)

Producers = self-sustaining organisms

- they trap light energy through photosynthesis (= process in which it converts CO2 + H2O into a simple carbohydrate) and produce food

- use the energy in the carbohydrate to produce proteins, starchs and lipids (all essential to living organisms)

-If plants are the only ones that can produce the fuel, how do animals get the fuel? (they eat them)

-What are the animals called if they CONSUME the plant?

Consumers = cannot make their own food (e.g. All animals, fungi and most bacteria)

-but do all animals eat the same stuff?

-what does a bunny eat? or a deer? or a dog? or a wolf or tiger?

(only plants, both, only other animals)

(older kids)

Explain the different types of consumers:

-primary consumers = only eat plants

-secondary consumers= eats the plant-eaters

-tertiary consumers = eats the secondary consumers

*classify the animals above into each of these categories (remember that some animals can be more than one type of consumer at the same time)

Decomposers = break down dead organisms and organic wastes.

Food chain = sequence of events where food, or energy, is passed from one creature to another until it becomes part of the top predator (has no natural predators) in the chain

Food Web = a complex system of interrelated food chains in an ecological community (remind them of the yarn web at the beginning of class)

Activity #3: Food chains & food webs

Objective: learn the actual interactions in Nature and how exactly it is all connected


-act a simple food chain (who eats who?)

-have them make their own food chain

(older kids):

-competition: divide class in 2 or 3 groups

-each group will be given a certain food web (they are told the region, e.g. Desert; or have them guess it)

-there will be one index card per animal on their food web and they will have 5-7 min. to complete their food web and the different interactions as fast as possible

-when time is up they will be given an illustration of their complete food web (theyíll realize where they were wrong and why)

-which team can fix their food webs the fastest?


IV- How our actions affect the whole system?

Objective: get the kids thinking about the consequences of our actions on an ecosystem (where everything is connected)

Activity #4:


-Take the poster board with the big food web on it (not drawn, but the pieces are taped on)

-Guide the kids through the different situations:

-cutting down trees

-who lives on the trees? (squirrels)

-what happens if they donít have a place to live?

*squirrels die- have one kid take out the piece of the squirrel

-if the squirrel dies what other animal has less food?

*take that piece off

*continue like that through the system until all the right pieces are taken out and ask them what happened to the ecosystem

*do the same for all the other scenarios

-pollution of the water

(fish and any animal that drinks the water is affected)

-new animal that nothing can eat it, but it can eat all the other animals

(all are affected)

-too much trash around

(many more rodents and flies, all the others are affected)

-have a different food web for each situation, so the kids can see the effects on different systems and theyíll learn more

-when done have them look at all the food webs and ask them if the ecosystem s in balance or healthy or just wellÖ. NO!!

(older kids)

Council of Animals

- Give every kid an index card with the name of an animal and short description of what their animal eats, who eats it, where it lives and things that can affect it

- Then give each one a paper plate and tell them that they have 5 min. to write the name of the animal they got and personalize it, by drawing it or making whatever will identify them as that animal (if short of time this part may be skipped, but if possible do it, so the kids will get more into their roles)

- Form a circle (the council of animals)

*We, the animals of the forest, have gathered in this special circle to discuss a terrible danger threatening us... HUMANS! Their crimes have been listed (show the list of crimes). Now we bring a human forth into this circle and through him we shall be able to communicate to all humans. My fellow animals, lets use this chance we have been given to show these humans how their actions are harming us, the animals of the forest.

- We (teacher) become the human who will be put in the middle of the circle

* Humans have been accused of several crimes towards nature

- Have every kid read one of the crimes

- Rules:

- Each crime will be dealt with one at a time

- Everyone must show the human how that action is affecting them (the animal they represent)

- Once all have spoken of the effect that action has on them, open the Council to see who has any suggestions for the humans on things they can do to cause less harm to the animals

- Move on to the next crime

- The situations may be the following:

- building a shopping mall (cut down lots of trees, noise pollution, pollution of the water because of construction)

- chemical spill on the waters

- people keep throwing trash

- introduction of exotic species

- hunting for pleasure

- clear land for agriculture (pesticides)

- a new highway that will cut through the middle of the forest

*Encourage kids to talk of new situations and problems they come up with, or use different ones that you think would be better




















Materials List: Ecosystems & Food Webs

Activity Materials


Qty needed

#2 Yarn ball

Depends on size



1 per teacher




blank paper or construction paper

1 per kid


Glue sticks (or regular if itís cheaper)

3-4 per teacher


Crayons or markers

1 box per teacher


Set of animal pictures

1 per kid


(older kids)


Set of index card w/ animal names on them

8 per teacher


Set of 20 string pieces

1 per group of 3-4


Complete diagram of food web

8 per teacher


#4 (Babies)


Poster board w/ big food web taped on it

2 per teacher



1 per teacher


(older kids)


Paper plates

1 per kid & SC & JC


Markers or crayons

Same box as before


Set of index cards w/ assigned animal & description

2 sets per teacher