Unit Overview

In Mosa Mack’s Interactions of Organisms Unit, students are led through a progression of three inquiry lessons that focus on three different types of interactions of organisms, including mutualism, predation, and competition.

Lesson Overview

Medium 1s 640Solve: Predator Mystery + Vocabulary Mind Map
Medium 2m 640Make: Use Multimedia Clues to Determine Organisms’ Interactions
Medium 3e 640Engineer: Engineer a Solution for an Invasive Species

Students work together to complete a Mind Map of Interactions of Organisms vocabulary before helping Mosa Mack solve the mystery involving the death of a clownfish within the coral reef ecosystem. By the end of The Solve, students discover a variety of relationships that exist among organisms in an ecosystem, including competition, predation, and mutualism. (75 mins)

Students will travel to three stations that represent three ecosystems. After examining the three types of interactions, including mutualism, predation, and competition, at each station, students will demonstrate their understanding through a creative presentation. (150-160 mins)

Students develop and design a solution to control an issue created by an invasive species. Students will draw a technical sketch or build a model of their solution. (200 mins)

Next Generations Science Standards

Construct an explanation that predicts patterns of interactions among organisms across multiple ecosystems.

Science & Engineering Practices

  • Constructing Explanations and Designing Solutions

Disciplinary Core Ideas

  • Interdependent Relationships in Ecosystems

Cross Cutting Concepts

    Inquiry Scale

    • Each lesson in the unit has an Inquiry Scale that provides directions on how to implement the lesson at the level that works best for you and your students.
    • “Level 1” is the most teacher-driven, and recommended for students in 4th-5th grades. “Level 4” is the most student-driven, and recommended for students in 7th-8th grades.
    • For differentiation within the same grade or class, use different inquiry levels for different groups of students who may require additional support or an extra challenge.

    Common Misconceptions

    • Students may initially think that the interactions in ecosystems only involve animals. Emphasize to students that plants also play important roles in interactions within ecosystems.
    • Students tend to limit their thinking of interactions in an ecosystem to biotic (living) components (example: animals interacting with other animals or plants). Emphasize to students that organisms interact with the abiotic (non-living) portions of the environment just as much as the biotic components. Abiotic components include water, temperature, amount of sunlight, and type of soil, and these can have major impacts on the health of the ecosystem.
    • Students tend to think that competition in an ecosystem is limited only to organisms of the same species competing for resources (example: two species of shark competing for same food source). Emphasize that competition can exist between different species of organisms competing for resources other than food as in the case of the American kestrel (falcon) and gray squirrel competing for nesting sites within the ecosystem.
    • Students tend to think that food is the only resource that animals compete for within an ecosystem. Emphasize to students that animals can compete for food, water, and shelter within an ecosystem.
    • Students may think that predation is a negative interaction in an ecosystem. Encourage students to think about how predator-prey relationships keep an ecosystem balanced.
    • Students tend to think that predator and prey populations are similar in size.Emphasize to students that prey populations tend to be larger in size due to faster reproductive rates and larger number of offspring/breeding cycles as compared to predator populations.


      • Ecosystem
      • Predation
      • Mutualism
      • Competition
      • Abiotic
      • Biotic

    Content Expert

    • Anjelica Gonzalez, PhD
      Donna L. Dubinsky Associate Professor Biomedical Engineering Yale University


    • Powerpoints for Make and Design
    • Vocabulary Cards
    • Solve Student Handout
    • Make Student Handout
    • Design Student Handout
    • Vocabulary Mind Map

    New: RocketLit Leveled Reading

    * To give our users the most comprehensive science resource, Mosa Mack is piloting a partnership with RocketLit, a provider of leveled science articles.

    • Can't We All Just Get Along?

      In cartoons, we might see different organisms being either friends or enemies, but in nature it's much more complicated. Symbiotic relationships change the way both organisms live, and some can be mutualistic (good for both). Some relationships are parasitic (take, hurt, take) and others are more commensal which help one organism involved and don't hurt the other.

    • What's Your Job?

      Different organisms have different jobs in an ecosystem, but sometimes they step on each other's toes. This article explains how organisms compete with each other for living space, the roles that they have and the niches that they fit into within their environment.

    • Life is a Competition

      Life is not easy, and often organisms must compete with organisms who are better suited than themselves for resources. One of the people who helped us to realize this and is tied to the theory of evolution was Thomas Malthus in his book "An Essay on the Principle of Population."