Strand III
Use Scientific Knowledge from the Life Sciences in Real-World Contexts


Science/Strand III
Content Standard 5
All students will explain how parts of an ecosystem are related and how they interact; explain how energy is distributed to living things in an ecosystem; investigate and explain how communities of living things change over a period of time; describe how materials cycle through an ecosystem and get reused in the environment; and analyze how humans and the environment interact. (Ecosystems)


Science/Strand III/Content Standard 5
Middle School


Science/Strand III/Content Standard 5/Middle School
Benchmark 1
Describe common patterns of relationships among populations.

Benchmark Clarification

Every organism in an ecosystem is directly or indirectly linked with other organisms in the ecosystem. Types of interrelationships may include:

  • Parasitism, where one organism benefits and one is harmed
  • Mutually beneficial relationships, where both organisms benefit (mutualism)
  • Competition, within a species or between different species for food, shelter, etc.
  • Predator and prey, where one organism (prey) is consumed by another organism (predator)

Students will:

  • Investigate producers, consumers, and decomposers
  • Explore the relationships existing organisms within an ecosystem.
  • Evaluate examples of relationships to determine the types of interrelationships that exist

Key Concept / Real World Context / Instructional Example / Assessment Example / Resources


Science/Strand III/Content Standard 5/Middle School/Benchmark 1
Key Concept
Participants and relationships:

  • predator
  • prey
  • parasite
  • competition
  • mutually beneficial


Science/Strand III/Content Standard 5/Middle School/Benchmark 1
Real World Context
Relationships among plants and animals in an ecosystem that are mutually helpful relationships:

  • insects and flowering plants
  • birds eating fruit and spreading seeds

Parasitic (harmful) relationships:

  • humans and mosquitoes

trees and mistletoeCompetitive relationships:

  • squirrels and seed-eating birds
  • weeds and garden plants


Science/Strand III/Content Standard 5/Middle School/Benchmark 1
Instructional Example

Benchmark Question: How are parts of an ecosystem related and how do they interact?

Focus Question: What types of interrelationships exist among populations in an ecosystem?

Students will write a journal entry listing relationships they have with other people that are helpful to them, harmful to them, or competitive. Students will share their lists with a partner. Students will watch a video about interrelationships and discuss the main concepts as a class. Students will take a walk to an area near the school and observe relationships in an ecosystem. With a partner, students will record their observations. As a class, students will share and compile their data. Students then will evaluate the relationships they have observed (helpful, harmful, competitive). The teacher will introduce key concepts and name the relationships that were identified.

Constructing: (SCI.I.1.MS.1), (SCI.I.1.MS.5).

Reflecting: (SCI.II.1.MS.1), (SCI.II.1.MS.3), (SCI.II.1.MS.5).


Science/Strand III/Content Standard 5/Middle School/Benchmark 1
Assessment Example

The teacher will present small groups with the following scenario:

”Survivor II, The Next Generation” is coming out next season. The rules have changed slightly. This season, teams of survivors will be placed on separate islands where they will remain for one month.

The teacher will select a variety of islands from around the world and write the names of the islands on slips of paper. Each team will draw a slip and then research the island. The winning survivors will be chosen as a result of their fine scientific journaling. To win the one million, you must discover a way to show all of the relationships you see among the different island populations on Earth.

Team journals should include the following information:

  • predator/prey relationships
  • parasitic relationships (parasite/host)
  • competitive relationships
  • mutually beneficial relationships

(Give students rubric before activity.)

Scoring Rubric






Description of relationships

Lists one relationship.

Describes two relationships.

Describes two complete relationships.

Describes three or more complete relationships.


Science/Strand III/Content Standard 5/Middle School/Benchmark 1


Ecology. MSU ASSESSMENT PROJECT. Michigan State University, 1997.


Pollack, Steve. Ecology. Dorling Kindersley, 1993.