Common Misconceptions about Biomes and Ecosystems

An ecosystem and its components (plants, animals, their interactions, and their surroundings) are all topics prone to misconceptions. Students may give human characteristics to, or anthropomorphize, plants and animals. They may struggle with ideas like predation, believe that only certain animals get eaten, or think that all organisms within an ecosystem “get along.” They may assume certain characteristics about groups of organisms such as carnivores based on a few examples or they may simplify the complex set of relationships represented by a food web. Finally, students may not understand that ecosystems are dynamic and change as a result of natural and human-influenced processes.

Another topic prone to misconception is adaptation. Students (and adults) often misinterpret or misuse this word to indicate that individual organisms intentionally change in response to changes in their environment. Many children’s books and web sites present some variation of this misleading notion in an attempt to simplify the concept or the reading level of material. As a result, adaptation is an extremely misunderstood scientific concept.

We’ve highlighted some common misconceptions about plants, food chains and webs, predator/prey relationships, ecosystems, and ecological adaptations that might be encountered in the elementary classroom. A more complete list can be found at the Overcoming Ecological Misconceptions web site. We’ve also included tools for formative assessment as well as lessons and suggestions for teaching correct scientific concepts.


MISCONCEPTIONS

Plants

Students may think… Instead of thinking…
Plants are dependent on humans. Humans (and all other animals) are dependent on plants.
Plants cannot defend themselves against herbivores. Plants have a range of defenses including external structures (sap, hairs, thorns, wax) and chemicals that either reduce digestibility or are toxic.

Students may have many other misconceptions about plants. For more information, please see “Common Misconceptions about Plants” in our March 2009 issue.

Food Chains and Webs

Students may think… Instead of thinking…
Food webs are interpreted as simple food chains. Food webs most accurately depict the flow of energy within an ecosystem. They depict a complex set of relationships that is not easily simplified to a food chain.
Organisms higher in a food web eat everything that is lower in the food web. Organisms higher in a food chain eat some, but not necessarily all, of the organisms below them in the food web.
There are more herbivores than carnivores because people keep and breed herbivores. There are more herbivores than carnivores because of the decreasing amount of energy available at each level of the food web.
Food chains involve predator and prey, but not producers. Producers are an essential part of all food chains and webs.
Decomposers release some energy that is cycled back to plants. Decomposers break down dead organisms, returning nutrients to the soil so they can be used by plants. Some decomposers are eaten by carnivores.
Carnivores have more energy or power than herbivores do. While some carnivores may be larger and require more food than some herbivores, they do not have more energy or power.
Carnivores are big or ferocious, or both. Herbivores are small and passive. Although some carnivores may be big and ferocious and some herbivores small and passive, there is a great diversity among each group of organisms.

Predator/Prey Populations and Relationships

Students may think… Instead of thinking…
Predator and prey populations are similar in size. Prey populations tend to be larger than predator populations.
The relative sizes of predator and prey populations have no bearing on the size of the other. The sizes of predator and prey populations influence each other.

Ecosystems

Students may think… Instead of thinking…
Varying the population size of a species may not affect an ecosystem because some organisms are not important. All organisms are important within an ecosystem. Varying a species’ population size may not affect all other species equally, but it will affect the ecosystem as a whole.
Ecosystems are not a functioning whole but simply a collection of organisms. Ecosystems include not just the organisms but also the interactions between organisms and between the organisms and their physical environment.
Ecosystems change little over time. Ecosystems change as a result of natural hazards, environmental changes, and human activity.
Species coexist in ecosystems because of their compatible needs and behaviors; they need to get along. Within an ecosystem, species compete for resources and feed on one another. Species live in the same ecosystem because of similar adaptations and environmental needs.

Ecological Adaptations

Students may think… Instead of thinking…
Traits are developed by individuals in response to the needs of the individual. Traits are developed across generations in response to environmental demands.

PROBING FOR STUDENT UNDERSTANDING

What do your students think? Formative assessment can provide insight into the ideas (correct and incorrect) that your students have before and during instruction. Teachers should note, however, that simply conducting formative assessment is not enough. Instead, teachers should reflect on the data and use it to plan and refine instruction.

One useful set of resources is a collection of formative assessment probes from NSTA Press. Volumes 1, 2, and 3 of Uncovering Student Ideas in Science contain 25 formative assessment probes each to help teachers identify misconceptions. Volumes 2 and 3 contain several probes that relate to biomes and ecosystems.

Related formative assessment probes in Volume 2 of Uncovering Student Ideas in Science:

Habitat Change” asks students to predict what will happen to an animal population if its habitat changes. It can be used to elicit student ideas about adaptation; specifically whether individuals intentionally change their physical characteristics or behaviors in response to an environmental change.

Related formative assessment probes in Volume 3 of Uncovering Student Ideas in Science:

Rotting Apple” asks students to think about why an apple eventually rots and disappears. It can be used to elicit student ideas about decay and the role of decomposers in an ecosystem.

Earth’s Mass” asks students to decide if or how the mass of the Earth changes as organisms eliminate waste and die. It can be used to elicit student ideas about the cycling of matter through ecosystems.


TEACHING THE SCIENCE

While teachers will need to tailor their instruction based on student needs and formative assessment data, there are some general suggestions and lessons for teaching correct scientific concepts about biomes and ecosystems.

Plants

Teachers should devote time to producers when teaching about ecosystems and food webs, including a discussion of the ways in which plants defend themselves against herbivores. For other ideas about teaching correct scientific concepts about plants, please see “Common Misconceptions about Plants” in our March 2009 issue.

Food Chains and Webs

Teachers should help students go beyond a basic understanding of food chains and webs by asking them to predict what would happen if various organisms were removed from the ecosystem. Teachers can also use these lessons to discuss the impact of pollution at all levels of a food web.

Cycle of Life 1: Food Chain
This lesson gives students the opportunity to learn about a variety of food chains in various environments.

Cycle of Life 2: Food Webs
Students will explore how various organisms satisfy their needs in the environments in which they are typically found. In addition, they will examine the survival needs of different organisms and consider how the conditions in particular habitats can limit what kinds of living things can survive.

Predator/Prey Populations and Relationships

Teachers can help students understand the relative population sizes and balance between predators and their prey by varying the numbers of predators and prey in the activity below. Students can observe what happens with fewer prey, fewer predators, and equal numbers of predators and prey.

The Wolf and the Moose
Students role play a predator/prey relationship. This activity could be modified to focus on any predator/prey pair found in the tundra.

Ecosystems

Teachers can help promote correct scientific thinking by focusing on the relationships between organisms and by asking students to predict what might happen if an organism was removed from the ecosystem or if the environmental conditions changed.

Investigating Local Ecosystems
Students in grades K-2 learn about ecosystems and relationships by observing their local environment.

Pond 1: Pond Life
Students explore how various organisms satisfy their needs within their environments and the kinds of relationships that exist between organisms within an environment.

Pond 2: Life in a Drop of Pond Water
Students continue to develop an understanding of a pond ecosystem by observing microscopic life and by discussing how single-celled living things might satisfy their needs for food, water, and air.

Making the Forest and Tundra Wildlife Connection
Students create tundra and boreal forest food webs using Alaska Ecology cards (pdf provided) and string. Teachers may want to use masking tape to tape down the web once it has been formed.

Ecological Adaptations

Teachers should take care to use language and select books that describe the concept of adaptation correctly. Elementary students may be more successful thinking about adaptations (traits and behaviors that help plants and animals survive) than about animals adapting to their environment. Students need to have a basic understanding of heredity and genetics to truly understand how species adapt, so this concept may be best left for the middle and high school years.

Animal Adaptations
Students analyze how the traits and behaviors of real and fictional animals reflect adaptations to their environment.


National Science Education Standards

Assessing and targeting student misconceptions about biomes and ecosystems meets the Life Science Content Standard for grades K-4 and 5-8 of the National Science Education Standards. The entire National Science Education Standards document can be read online or downloaded for free from the National Academies Press web site. Science Content Standards can be found in Chapter 6.


This article was written by Jessica Fries-Gaither. For more information, see the Contributors page. Email Jessica at beyondpenguins@msteacher.org.

Copyright April 2009 – The Ohio State University. This material is based upon work supported by the National Science Foundation under Grant No. 0733024. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under anĀ Attribution-ShareAlike 3.0 Unported Creative Commons license.

Leave a Reply

Your email address will not be published. Required fields are marked *