1. To the teacher:
This CPO Science PowerPoint presentation is designed to guide you through the process of presenting the lesson to your students. The presentation uses a 5-E teaching model: Engage, Explore, Explain, Elaborate, and Evaluate.
The PowerPoint Slide notes indicate where you may want to bring in various lesson elements such as quizzes, readings, investigations, animations, and practice materials. Additional science background information is provided in the slide notes where appropriate. You can view these notes by selecting “View,” then “Normal.” You will see the notes pane at the bottom of the PowerPoint workspace. Additionally, the slide notes are available as a separate document, accessible from the lesson home page.
The slides that follow are intended for classroom use.
About the slide notes:
The slide notes for this presentation are available in a separate document that you can print and look at while you use the slides. You can access the slide notes document from your teacher lesson home page.
Enjoy the lesson!

2. What’s in an ecosystem?
A sea otter wakes from a nap and unwraps itself from the kelp that kept it from floating away. The otter dives to the ocean floor in search of sea urchins that feed on the kelp. The otter brings an urchin to the surface, floats on its back in the sunshine, cracks open the urchin with a rock, and eats it.
Can you name at least three non-living and three living things that interact in this coastal marine ecosystem?
What types of ecosystems are found where you live?
ENGAGE:
Read the description of the sea otter in its ecosystem together with your students. Help them to identify three non-living parts of the ecosystem (sunshine, sea water, rock) and three living parts (sea otter, sea urchin, kelp). Later, come back to the description and ask students to identify the producer/consumer relationship (kelp/urchin) and the predator/prey relationship (otter/urchin) found in the paragraph.
Ask students to describe ecosystems (woodland, marsh, prairie, etc.) found where they live. Help them identify living and nonliving parts of these ecosystems. Keep a class list so that later, you can discuss the producer/consumer, predator/prey, and parasite/host relationships found in each ecosystem.

3. Time to investigate! Complete the lesson investigation: Food Webs
EXPLORE:
Lead the lesson investigation: Food Webs. Afterward, assign the student reading.

4. Producer/consumer relationships
A producer is a living thing (like a plant) that makes its own food.
A consumer must feed on other living things for food and energy.
Herbivores consume only plants.
Carnivores eat only animals.
Omnivores eat plants and animals.
What is the producer in the marine ecosystem shown here? What types of consumers can you identify?
EXPLAIN:
The seaweed is the producer in the marine ecosystem pictured. Remind students that most but not all producers use photosynthesis to make food from sunlight. Draw their attention to the hydrothermal vent ecosystem featured on pages 8 and 9 of the student reading. What process do the producers in that ecosystem use to make food?
The names of the animals depicted can be found on page 6 of the student reading. Herbivores include worms, zooplankton, and snails. The rest of the animals depicted are carnivores. No omnivores are shown. Ask students if they can name any marine omnivores. Some species of sea stars are omnivores. They eat algae and small mollusks.

5. Predator/prey relationships
Predators are animals that hunt and feed on other animals.
Prey are animals that are eaten by other animals.
Can you identify three predator/prey relationships in the freshwater ecosystem at right?
EXPLAIN:
There are many predator/prey relationships depicted. Point out to students that an animal may be both predator and prey. For example, the diamond back water snake is a predator of the green tree frog and prey for the great egret and great blue heron. Ask students to think about their investigation experience, and then discuss what would happen if the grasshopper disappeared from the ecosystem. How many of the other organisms would be directly affected? (Sunflowers and cattails might be more abundant. But wolf spiders, green tree frogs, and red-winged blackbirds would lose a food source. If their populations decline, the water snake, egret, and great blue herons would be affected as well.)

6. Parasite/host relationships
A host is an organism that shares its energy resources with another organism.
A parasite is an organism that takes energy resources from another organism, causing harm to its host.
Which organism is the parasite in each photo?
EXPLAIN:
The first picture shows mistletoe, a parasitic plant. While mistletoe can make some of its own food via photosynthesis, it attaches to mature trees and extracts water and nutrients from its host plant. Mistletoe can severely weaken and sometimes even kill its host.
The second photo shows a tomato hornworm caterpillar with braconid wasp cocoons attached to its back. The female wasp laid her eggs under the skin of the hornworm. The wasp larvae fed on the caterpillar’s tissue. When they matured, the larvae spun cocoons attached to the hornworm’s back. The hornworm often does not survive for long after the wasps emerge. While the wasps are harmful to their hosts, they are considered beneficial insects from a human perspective because they control the population of tomato hornworms which, if left unchecked, can cause significant damage to a tomato crop.

7. Relationships in a terrestrial ecosystem
Describe two producer/consumer relationships in the terrestrial ecosystem food web pictured at right.
Describe two predator/prey relationships in the food web.
EXPLAIN:
Students previously learned about producer/consumer and predator/prey relationships in marine and freshwater ecosystems. Now ask them to apply what they learned to a terrestrial ecosystem food web.

8. Time for Practice! Complete the lesson practice activity:
Ecosystem Interactions
ELABORATE:
You may wish to discuss two terms that were introduced to students in the reading segment and will be reinforced through the lesson practice activity.
The terms are competition, which occurs when two or more species in an ecosystem depend on the same limited food supply; and symbiosis, which describes a long-term interaction between two different species where at least one species benefits and the other is unharmed.

9. Show what you know!
Try the lesson’s interactive quiz, or complete a quiz that your teacher can print out for you.
Hint:
You might want to review your lesson reading piece one more time before trying the quiz.
EVALUATE:
Print out the 10-question quiz for students to complete, or have students work individually at computers to complete the interactive quiz they can access from the multimedia lesson home page.