Lesson 3: Networking
(60 minutes)
Key Question: How does matter and energy move through and ecosystem? What functions do organism serve in an ecosystem?
Learning Objectives
- Students will model the ways matter and energy move through a corn field ecosystem by creating food chains and food webs.
- Students will identify the roles of producers, herbivores, carnivores, omnivores, scavengers, and decomposers.
Materials
Procedures for Instruction
Assess prior learning and engage students:
- “What were the categories of organisms we identified in our ecosystem?”
- “How else could we categorize these organisms? Did anyone have ideas?”
- Encourage the idea that organisms can be categorized by the role they play in the ecosystem.
- (“Can we group all organisms together that create their own food through photosynthesis?” “…that eat plants only?” “…that eat only other animals?”
- “Where does the energy come from for organisms to live?”
Propose food chains in science notebooks.
- Instruct students to get out their notebooks, review the organisms they observed in the ecosystem, or refer to Kansas Cornfield Organism Cards
- Propose new food chains that contain at least 4 organisms. Indicate the relationship with arrows.
- After 5-10 minutes, have them share their food chains with a partner and compare.
Discussion to explore food webs with such questions as:
- “How many of your food chains have common players or organisms?”
- (e.g., how many have grasshoppers? Birds? Plants?)
- “Do they play the same role in each food chain?”
- “Are simple food chains the only way all these organisms relate to each other?”
- “Let’s see if we can model a corn field ecosystem!”
Play a game to create a model of an ecosystem food web using organism cards.
(If you use student cards, make sure there is a balance between organisms: plants, herbivores, omnivores, carnivores, scavengers, decomposers. Also, cards with Sun, Air, Water, Minerals should be included.)
- Instruct students to retrieve their organism card with the binder clip or paper clip. Each student should have a card with an organism that they make visible to everyone. Or provide each student with Kansas Cornfield Organism Card
- You (the teacher) have the cards Sun, Air, Water, and Minerals (or to simplify, just Sun). You also hold the ball of yarn.
- Arrange everyone in a circle. Tell students that you all are going to create a model of an ecosystem in a corn field, with the yarn showing connections between organisms. Tell them they need to think about what organisms they could connect their own organism to.
- Going around the circle, everyone announces their organism and a little key information about how it gets its food.
- You start with the yarn. Clip the end of the yarn to your card(s), then toss the ball of to someone holding a plant card (allowing the yarn to unfurl) and say, “I am the Sun, the Air, the Water, and Minerals. Plants need me to create food.”
- That person (who represents a corn stalk) catches the ball of yarn. S/he secures the yarn to his/her card, and then tosses the ball of yarn to another person representing an herbivore (such as a grasshopper) that eats it, saying something like, “I am a corn stalk and I get my food from the sun, air, water, and minerals. Grasshoppers eat my leaves for energy.” Each student should indicate how their organism gets its food, and the organism that eat it.
- Continue around the room until everyone has a piece of the yarn fastened to their card. If there are some leftover organisms that have not joined the web, bring the yarn back to you and start a new layer of the web (while everyone still holds onto the existing one).
Connect vocabulary with concepts.
- Students return to desks and open science notebooks.
- Ask the students if they understand the difference between a food chain and a food web, and make notes on the board or anchor chart. Have students write the definitions in their notebook. (Both are models depicting relationships among organisms and how matter or food moves through an ecosystem.)
- Food Chain: A model showing linear links of how matter moves in an ecosystem.
- Food Web: A model showing interdependent and overlapping links of how matter moves in an ecosystem.
- “Which is more complex? In what ways is it more complex?”
Lead into understanding the terms for the roles that organisms play in the ecosystem
Vocabulary list:
- Ask students to suggest names for the roles that organisms play in the ecosystem. Example: plants can be considered “Food Creators” or “Sunlight Chemists” or “Producers,” since they produce their own food through photosynthesis.
- “What might you call the organisms that eat plants?” and so on. Using Think-Pair-Share, or Timed Writing, give students 5 minutes to generate names for the different roles in a food chain/web.
- Guide class discussion, making notes on anchor chart or board.
- “If plants are called producers, what did you call the organisms that eat them?”
- Share out different student terms, encouraging them to generate descriptive terms and definitions. Have fun with this. They will likely offer terms scientists use along with others. The goal is to have them construct the definitions of the concepts themselves, with you helping them to refine and restate their understandings.
- In this fashion, solicit student names for each level in the food web, and end offering (or circling) the term scientists use:
- Producers: Organisms that produce their own food by photosynthesis (mostly plants)
- Consumers: Organisms that eat other organisms
- Herbivores: Organisms that eat plants (grasshoppers, bees, rabbits, deer)
- Omnivores: Organisms that eat both plants and animals (bears, coyotes, chickens)
- Carnivores: Organisms that hunt and eat other animals (hawks, snakes, mountain lion, coyote)
- Scavengers: Organisms that search for and eat dead animals (turkey vulture, crows, flies, cockroaches, raccoons, bears)
- Decomposers: Organisms that transform dead and decaying organisms or waste into material useable by other organisms such as plants (fungi, bacteria, termites, earthworms)
- “You are thinking just like scientists, and in fact have come up with many of the same categories they have!”
- “Can one organism be in more than one category?” (yes) “Can you give an example?”
- “Which category would be the largest by mass?”
- (producers, because energy is lost at every level since organisms consume energy to live, grow, and reproduce themselves – they pass on less energy)
- Another way scientists describe food webs is to indicate:
- Producer (living things that makes its own food)
- Primary Consumer (eats producer)
- Secondary Consumer (eats primary consumer)
- Tertiary Consumer (eats secondary consumer)
- Decomposer (organisms that break down dead plants and animals for food)
Have students record vocabulary terms and definitions in science notebook
- Create a corn field food web model with labels in science notebook.
- Instruct students to draw a food web in their science notebook and label each organism using the vocabulary terms.
- Remind them to include the Sun, Air, and Water as the starting point.
- Give students 10-20 minutes to complete these.
- OR use technology such as
Conclude with this quote:
When we try to pick out anything by itself, we find it hitched to everything else in the universe. – John Muir
Assessments
- Formative assessments during discussion and activities:
- Assess students’ concepts of the roles organisms play in an ecosystem. Do they realize some organisms play multiple roles?
- Assess students’ understanding of the interrelatedness of all organisms in the food web.
- Assess students’ understanding that more producers are needed in a food web than consumers, and more primary consumers than secondary consumers, because energy is used/lost at each level.
- Summative assessments:
Information for Teachers
- Students can access further information and examples of food chains, food webs, producers, consumers, and decomposers at the following websites: