Lesson Plan • The Web of Life • Science Camp • IASD 2012
1
!"#$%#&$'($)*(#!
Lesson Plan
From a lesson by David T. Crowther,
University of Nevada, Reno
Teacher: Annie Martin
Subject: Science
Grades: 5th-8th
____________________________________________________________
Purpose and Objective:
The purpose of this lesson is to help students understand the interconnectedness
between the different levels of a food web and the delicate balance maintained
within an ecosystem. Students will be able to create a food web and label the
different levels as producers, primary consumers, secondary consumers, and
tertiary consumers. Students will also be able to show how energy flows through
a food web.
Materials List
• A huge ball of yarn (The super sized ball of worsted yarn from Wal-Mart
works fine)
• 3x5 cards (100)
• Copies of There Once Was a Daisy rap song by the National Wildlife
Federation 1989 (see below)
• Paper
• Colored pencils/markers
• Large bowl of popcorn (2-3 bags of microwave popcorn or 1-2 cups of
popcorn kernels and a microwave or an air popper)
• One plastic cup for each student
• 16 cards labeled “grass”
• 8 cards labeled “grasshopper”
• 4 cards labeled “robin”
• 2 cards labeled “snake”
• 1 card labeled “hawk”
• 1 card labeled “vulture”
Lesson Plan • The Web of Life • Science Camp • IASD 2012
2
Preparation
• Before class prepare the huge ball of yarn so that it can be thrown easily.
• Next, figure out how many people will be involved in the activity and
prepare enough 3x5 cards so that there is a proportionate representation
of grass, grasshoppers, robins, snakes, one goshawk, and a vulture.
• Note: In the trophic pyramid there are far more producers (grass) than
other consumers. Therefore for a class of 28 students, make about 12 grass
cards, 8 grasshopper cards, 4 robin cards, 2 snake cards, 1 goshawk card,
and 1 vulture card. Please see below for picture cards.
• Use pictures on the front of the cards for clarification if necessary.
• On the back of each card write the that role the organism fills in the
trophic pyramid: producer, primary consumer, secondary consumer,
tertiary consumer and for the consumers, the type of consumer (herbivore,
carnivore, omnivore).
• You can put a string through each card so the students can wear them.
• Make copies of the There Once Was a Daisy (NWF, 1989) rap song for each
student. Please see below.
• Make a large bowl of popcorn, either air popped or 2 bags of microwave
popcorn.
Lesson Plan • The Web of Life • Science Camp • IASD 2012
3
1. Engagement (Please click here to see a video of the lesson.)
• Put the students into four groups. Explain that they are going to do a rap
song that deals with food chains. Hand out a copy of There Once Was a
Daisy (NWF, 1989) song to each person. Give each group of students a role
in the song, e.g. Bugs, Wrens, Snakes, and Foxes. Make sure everyone
knows that a wren is a small bird that eats both bugs and seeds. The entire
class will sing both the All and the Daisy parts.
• After the song go to the board and have the students tell you what the
food chain was in the song. Draw the simple food chain on the board with
arrows connecting who eats whom as the students provide the
information. See example below:
Fox
!
Snake
!
Wren
!
Bugs
!
Daisy
II. Exploration
1. Hand each student one of the pre-made 3x5 cards with an animal
assignment on it (See preparation section). Have all the students with grass
on their cards stand and present themselves. Repeat this process with each
of the categories of Grasshoppers, Robins, Snakes, and Goshawks. Do not
introduce the Vulture at this time. Make sure to spread out the members
of each category so they are not standing/sitting together.
2. Beginning with a student who is designated as a grass, have them hold the
end of the yarn and toss it to someone who would eat grass (the
Grasshopper). The person who is designated as a Grasshopper then throws
the ball of yarn to the person who would eat the Grasshopper (the Robin)
WHILE KEEPING HOLD OF THE YARN. (The student will hold yarn in
one hand and not let go of it while throwing the ball of yarn. This part gives
Lesson Plan • The Web of Life • Science Camp • IASD 2012
4
students trouble sometimes.) The Robin then holds onto the yarn and then
tosses the ball to the Snake. The Snake then holds onto the yarn and
tosses the ball to the Goshawk. Since the Goshawk is the Tertiary or Top
consumer in the chain, the ball then gets thrown back to a person who is a
grass and the process starts all over again. You will soon see how a single
chain becomes a complex Web of Life!!
3. Once everyone has a chance to hold at least one piece of the yarn, play
some nature music (any kind will do) and have the students move to the
beat so they can get a feel of the interdependency of the web. Music is
optional and you can just have the students move around a bit. Remind the
students they need to hold on tight to their pieces of the yarn web.
4. When the music is off or the students have had a chance to move a bit
introduce the following scenario:
I have just been informed that a developer has just received permission to build a
new golf course and resort lodge in this wonderful ecosystem that we have
created. The developer has hired a bulldozer to clear the grass and plants from
the field. If you were grass or a plant you are now dead and must let go of the
yarn. Allow the other students to feel the string go slack. Next, if you were a
consumer of grass your food source is now gone and you are dead. The
Grasshoppers let go of the string. Do the same for the Robins and the Snakes.
The Goshawk no longer has food here and is able to travel to a new ecosystem to
find a food source. Now all that is left is a bunch of dead and dying parts to a
once healthy ecosystem. There is only one person who benefits from the travesty
and that is the Vulture. The Vulture flies in and cleans up the mess. (If you have
an aid in the class you can ask them to play the role of vulture, otherwise have
the student vulture gather up all the string into a pile and you can roll it up later.)
III. Explanation
Time for Teacher Talk: Debrief the previous two activities, putting each step of
the food chain on the board, discuss with the class what part each organism
played in the food chain. (E.g. the daisy/grass were the producers- it is called a
producer because it makes its own food through the process of photosynthesis
[be sure to add the sun to the board as the main source of energy for producers.]
The rest of the organisms in the food web are consumers-they are consumers
because they cannot make their own food, but must rely on eating other things to
survive. The Bug and the Grasshopper are a special type of consumer (1st level or
primary consumers) that only eat plants, called herbivores. The Robin and the
Wren are also consumers (2nd level or secondary consumers) but because they
eat both bugs (meat) and seeds (plants) they are called omnivores. The Snake,
Goshawk, and Fox are also consumers (3rd level or tertiary), but because they
Lesson Plan • The Web of Life • Science Camp • IASD 2012
5
primarily eat meat we call them carnivores. The Goshawk and the Fox are at the
top of the food chain. An animal that has no predators in a food chain is the top
consumer. Additionally, the role of the decomposers must be discussed as they
complete the life cycle in the food web, breaking down the organisms into the
basic elements that are required of plants.
Draw a pyramid on the board adding in the organisms at each level and including
the terms producers, herbivores, omnivores, carnivores, secondary, tertiary,
primary consumers, decomposers. Label all the levels jointly as Trophic Levels.
You can draw stick figures for each level as well. Be sure to include the sun. This
is our food web and it is a system.
Next talk about the energy in this system. Have you ever noticed that there are a
lot of grass and plants around and a lot of bugs but not quite as many bugs as
there are plants? There are quite a few small birds around but not quite as many
as there are bugs. There are a few snakes and fewer large birds. As you go up the
food chain, there are fewer members in each level. Ask students where the
energy enters the system (sun). Draw arrows from the sun to the plants. Next
ask the students if all the energy the sun provides to the plants get passed on to
the primary consumers. Ask leading questions to get to the fact that only a small
portion of the energy is passed up. The producers for their own life processes
like growth and reproduction use most of the energy. Talk about this concept
between each level adding arrows to represent the energy moving up the system.
Explain the rule of tenths (Only about 10% of the energy consumed or used by an
organism gets passed up to the next level. About 90% of the energy consumed or
used by the organism provides for the life processes of that organism.) Add
numbers going up the side of the pyramid with the arrows e.g. 10%, 10%, 10% etc.
Now apply some simply numbers to that such as 100,000 plants feed 10,000 bugs
who feed 1,000 small birds who feed 100 snakes who feed 10 goshawks or foxes.
Move on the elaboration to demonstrate the energy flow and loss to the system.
1V. Elaboration
Students should still have their cards from the food web activity. Have the Grass
students come up and sit in a row (or stand if sitting is inappropriate). Next, have
the Grasshopper students come up and sit in a row behind the Grass students.
Then, have the Robin students come up and sit in a row behind the Grasshopper
students. Have the Snake students come up and sit in a row behind the Robin
students. Last, have the Goshawk student come and sit behind the Snake
students. Pass out a plastic cup to each student.
Lesson Plan • The Web of Life • Science Camp • IASD 2012
6
Explain that you are the sun in this activity and you are going to pass out energy in
the form of popcorn. Ask that no one start eating his or her popcorn until
instructed to do so. They do not have to eat the popcorn at all if they don’t want
to eat it.
Fill each of the Grass students’ cups with popcorn. Now ask that each of the
Grass students pass back about a tenth of their popcorn to the Grasshopper
students. Then ask the Grasshopper students to pass back about a tenth of their
popcorn to the Robin students. Continue in the fashion until everyone has some
popcorn. There might not be much by the time it gets up to the top consumers.
Let the students know that the only way they can get more popcorn is if they get
it from the level below themselves. The sun will continue to fill the plants with
energy. Each time the plants get a refill they must pass on about a tenth of the
energy before they can eat their popcorn. Now let everyone eat the popcorn
they would like and let the system run for a few minutes. Once everyone has had
a chance to pass on and obtain additional popcorn you can stop the system and
move on to the evaluation.
Allow the students to take a cup of popcorn back to their seats and talk about
the simulation they were just involved in. The short debrief should include
thoughts about the upper trophic levels depending on the lower ones and how
enough energy doesn’t always get to the top. Discuss what might happen in real
life when there isn’t enough food for the upper trophic levels.
5. Evaluation
Have the students draw a food pyramid in their science notebooks with examples
at each trophic level and including the flow of energy through the system,
including the terms:
•
•
•
•
•
•
•
Primary consumers
Secondary consumers
Tertiary consumers
Decomposers
Producers
Omnivore
Herbivore
Lesson Plan • The Web of Life • Science Camp • IASD 2012
7
• Carnivore
• Top consumer
• Energy
Challenge the students to build their pyramids with local organisms. Walk around
and ask students to explain their pyramid. Encourage them to use the appropriate
terminology. Check that students are making an entry in their notebooks with the
terms.
National Science Education Standards Connection:
5-8 Science as Inquiry, content Standard A, Abilities necessary to do
scientific inquiry.
5-8 Life Science, Content Standard C, Populations and Ecosystems.
!"#$%&#'
(")%*+,
!"#$%&
'"()"#%
!"#$%&'()*+%
!"#$%
!"#$$%&''("
!"#$$%#&'