Life Science
Interdependence within the Earth System

The interrelationship and interdependence of organisms generate dynamic biological communities in ecosystems.

Benchmark: Carrying Capacity

Describe factors that affect the carrying capacity of an ecosystem and relate these to population growth.

Benchmark: Changes in Ecosystems

Explain how ecosystems can change as a result of the introduction of one or more new species.

For example: The effect of migration, localized evolution or disease organisms.


Standard in Lay Terms 

MN Standard in Lay Terms

Organisms within an ecosystem interact with each other and in turn influence the life processes and survival of each other.

Big Ideas and Essential Understandings 

Big Idea

All organisms live within a system wherein they interact with other organisms.  They do this in such a way as to influence the survival of each other in a dynamic balance we call an ecosystem.

Benchmark Cluster 

MN Standard Benchmarks  Describe factors that affect the carrying capacity of an ecosystem and relate these to population growth.  Explain how ecosystems can change as a result of the introduction of one or more new species.

The Essentials

See this page.


NSES Standards:pg 186

The atoms and molecule on the earth cycle among the  living  and nonliving components of the biosphere.

Energy flows through ecosystems in one direction;......

Organisms both cooperate and compete in ecosystems. ...

Living organisms have the capacity to produce population of infinite size, but environments and resources are finite.

Human beings live within the wold's ecosystems.  Increasingly, humans modify ecosystem as a result of population growth, technology and consumption.

AAAS Atlas:  See Benchmarks below

Benchmarks of Science Literacy

Benchmark 5E/3 The chemical elements that make up the molecules of living things pass through food webs and are combined and recombined in different ways.  At each link in a food web, some energy is stored in newly made structures but much is dissipated into the environment as heat.  Continual input of energy from sunlight keeps the process going.

Benchmark 4C/1 Plants alter the earth's atmosphere by removing carbon dioxide from it, using the carbon to make sugars and releasing oxygen.

Benchmark 5D/H1 Ecosystems can be reasonably stable over hundreds of thousand of years. As any population grows  its size is limited by one or more environmental factors; availability o food, availability of nesting sites, or number of predators.

Benchmark 3C/H4 the human species has a major impact on other species in ways, reducing the amount of the earth's surface available to those other species, interfering with their food sources, changing the temperature and chemical composition of their habitats, introducing foreign species into their ecosystem, and altering organism directly through selective breeding and genetic engineering.

Benchmark 5D/H3 Human beings are part of the earth's ecosystems. Human activities can, deliberately or inadvertently, alter the equilibrium in ecosystems.

Benchmark 5D/H2 If a disturbance such as flood, fifire or the addition or loss of species occurs, the affected ecosystem may return to a system similar to the original one, or it may take a new direction, leading to a very different type of ecosystem.  Changes in climate can produce very large changes in ecosystems.

Framework for K-12 Science Education

Ecosystems have carrying  capacities,  which are limits to the numbers  of organisms  and populations they can support. These limits result from such factors  as the availability  of living and nonliving resources and from such challenges as predation, competition, and disease. Organisms would  have the capacity  to produce  populations of great size were it not for the fact that  environments and resources are finite. This fundamental tension  affects the abundance (number  of individuals)  of species in any given ecosystem.  12LS2.A

A complex  set of interactions within  an ecosystem can keep its numbers  and types of organisms  relatively constant over long periods  of time under  stable conditions. If a modest  biological  or physical disturbance to an ecosystem occurs, it may return  to its more or less original  status  (i.e., the ecosystem is resilient), as opposed  to becoming  a very different  ecosystem. Extreme  fluctuations in conditions or the size of any population, however,  can challenge the functioning of ecosystems in terms of resources and habitat availability.  Moreover, anthropogenic changes (induced  by human  activity) in the environment—including habitat destruction, pollution, introduction of invasive species, overexploitation, and climate change—can  disrupt an ecosystem and threaten the survival of some species.  12LS2.C

Common Core Standards

Common Core Standards

Math standards can be easily incorporated into this topic. 

Math  Make reasonable estimates and judgments about the accuracy of values resulting from calculations involving measurements.

Students are encouraged to create ecological pyramids of energy transfer and biome structure.   They may create computer simulations of mathematical models of predator/prey relations and/or population growth.   One example is a project in which a student created a simulation of the optimum removal of buckthorn in an area which encouraged native plant propagation but was still reasonably attainable.

Math   Design simple experiments and explain the impact of sampling methods, bias and the phrasing of questions asked during data collection.

This standard can be addressed with all data collection methods, statistical analysis and graphing can be done

Common Core Language Arts:   Students can write a laboratory report in the proper form and using their knowledge of technical writing skills.  Common core standards addressed:

RST.9-10.1. Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations or descriptions.

RST.9-10.2. Determine the central ideas or conclusions of a text; trace the text's explanation or depiction of a complex process, phenomenon, or concept; provide an accurate summary of the text.

RST.9-10.3. Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.

The Nature of Science and Engineering:,   Students might design a way for agriculture to increase the carrying capacity of a field through the use of biotechnology such as bioremediation, soil retention and general sustainability of resources.    Reference to American Indian practices.


Student Misconceptions 

1.    Many students fail to see the link between fluctuations in population size and related environmental issues (Munson 1991).T

2.    There are more herbivores because they have more offspring. and a species high on the food web is a predator to everything below it.  They are numerous in order to fulfill a demand for food by another population. (Leach et al., 1992 - Atlas  Vol II pg 32)

3.    Some students may think that populations coexist in an ecological  system because of their compatible needs and behaviors; they need to get along( Munson, 1991 - Hard to Teach Biology Concepts pg 219)

4.    Students may think that the relative sizes of predator and prey populations have nothing to  do with each other (Gallegos et al. 1994 - Hard to Teach Biology Concepts pg 219)


Mr. R told his students to be prepared for studying outside for the next unit on ecology.  Dress for the weather was written on the board.  On a bright sunny fall day, the class went outside, groups of students were given quadrant to observe and record their observations in their notebooks.  Some of the quadrants were in a  nearby forest, the football field, next to the school parking lot, etc. Every month, the students went back to their quadrant to make observations.  Each time, when they returned to the class, they drew and posted pictures of the food webs of their "mini ecosystem on the wall which included producers, consumers and others (including pollinators). As a class, they discussed how it looked different after each observation.  Students also conducted historical research of what their was ecosystem was in the past (i.e. forest, farmland, grassland, etc.)  In the Spring, the students made presentations about their ecosystem predicting how it will change in the future because of human impact.

Alternative Vignette Activity

Bottle Biology:   Creating an ecosystem using 2 liter pop bottles is a very effective way to observe an ecosystem when going out into the environment is not an option.  Bottles can be cut in a variety of ways to create water ecosystems, land ecosystems and combinations of the two.  Organisms from plants to invertebrates (and some vertebrates) can be included to fulfill their role in the system.  Observations can be made daily to determine changes and find balance in the ecosystem.                    


Instructional Notes 

Suggested Labs and Activities   How many Bears can Live in this Forest?

This is an activity which is published by "Project Wild".   In this game the students become bears hunting in the forest.    Food is spread out on the ground and it is given a variety of different point values depending on the type of nutrition it has available.   The bears hunt and return the food to their dens.   At the end of the game, the food and nutrient values are added up to determine which of the bears survive and which do not.    Invasive Exotics

Introduction to the invasive exotics that have been introduced in Minnesota.   An especially interesting conversation takes place when the great lakes is discussed.   Invasives arriving in the great lakes include zebra mussels, lampreys, gobies etc. through the ballast water of ships after the canal was opened.  Salmon are placed into the great lakes to control the ale wife population after the lamprey have disseminated the trout.  Supplies needed include a good map of the Great Lakes and pictures of the cast of characters.  After students identify the invasive species, they make a "Most UnWanted" Brochure or posters in order to educate  others about the problem of invasives.   Buckthorn projects

Buckthorn poses a very real problem. (at least in Minnesota).  After learning about Buckthorn students can begin a variety of projects from pulling buckthorn to researching possible ways to control it's spread.  Some interesting inquiry can be done with the berries. From past research it was found that they need to be exposed to acid in order to speed up germination.   Students have also discovered that they make an excellent pH indicator as they turn a variety of colors at various pH's (similar to effect with red cabbage).  Active inquiry based research can be done on any available invasive exotics and can lead to some very intriguing discussion with very engaged students.

Instructional suggestions/options

Keeping a journal in a science notebook of the changes in an ecosystem over time helps students with organization and teaches the importance of detailed observations.  An "Adopt a Tree" journal is a nice way to do this in which students watch the comings and going in their favorite tree over a period of time.

Preconceptions - circle map of ecosystem listing all words/phrases that students associate with ecosystems.  In a larger circle outside of this circle, write words that describe students personal experiences that have influenced what was written in the inner circle.

Coupling classroom or computer modeling and field studies.   Data can be recorded in spreadsheets or in computer simulations and the impacts of changes can be immediately seen.

Situated learning (familiar ecosystems.   Studying and observing ecosystems that are on school grounds,backyards and neighborhood parks.

Connecting the growth of the human population on the carrying capacity of the Earth.   Students can analyze growth curves of various human populations.  Which ones are sustainable and which ones are reaching inevitable carrying capacity.  

Instructional Resources 

Additional resources

NSTA Press - Invasion Ecology

Strange intruders are invading our part of the world, threatening our environment and our economy. These newcomers and their impact on our ecological balance are the focus of Invasion Ecology, a new book that teaches students to investigate the behaviors of nonnative and native species.

The Teacher's Edition explains how to guide highly sophisticated inquiry and conduct interactive research. Materials are classroom-ready and include detailed background information as well as sample assessment tasks and rubrics. Student Edition also available

Project Wild

Project WILD is one of the most widely-used conservation and environmental education programs among educators of students in kindergarten through high school.  The program emphasizes wildlife because of their intrinsic, ecological value, as well as their role in teaching how ecosystems function.

New Vocabulary 


  • Carrying capacity - Largest number of individuals that a particular environment can support.
  • Invasive Exotic species - a species that is not native to a specific area and whose introduction does or is likely to cause or harm native species because it has not evolved with native species and can out-compete them.
  • Predation - interaction in which one organism (the predator) captures and feeds on another organism (the prey)
  • Competition  - More than one kind of organism attempting to use the same essential resources in the same place at the same time.
Technology Connections 

The Globe Project

North American Amphibia monitoring Program or Frogwatch USA

U.S. Forest Service I Tree website incorporates online monitoring programs - one to assess urban ecosystems and one to assess street tree populations.

Podcast transcript of worms as invaders

Cross Curricular Connections 

Math - exponential growth curves of populations.


Assessment of Students

Include questions designed to probe student understanding of concepts, both formative and summative.   Identify taxonomic level of questions. Formative - In discussion groups, students simulate a predator prey scenario and discuss the effects of the populations on each other. Formative - Students explain the effects of a specific invasive exotic (buckthorn, zebra mussels, purple loosestrife) and then describe how the predator prey situation differs from a normal native situation.    Co-evolution should be discussed. - Discuss the importance of biodiversity.

Summative - Students debate an environmental issue involving the introduction of an invasive exotic into the Great Lakes ecosystem such as the salmon.  The students look at the issue from several angles including the fact that the alewife is overpopulating, the sea lamprey has taken out the alewife's predator - trout and the salmon has a market value  (it would be better if a local issue  can be used).  Students role play  of different stakeholders.

Assessment of Teachers  1. Explain the concerns about the Earth's capacity in terms of carrying capacity.  What are some of the limiting factors for the human population?

Answers may include:   Food, Disease, Waste products, psychological over-crowding and others.   Salmon are an ocean fish.  They only return to freshwater when they lay eggs and reproduce.   How do you explain their presence in the great lakes where they no longer have access to salt water?   Who put them there and why?  How are they connected to the alewife, lake trout and sea lamprey

Answer:   Salmon were put into the great lakes after the lamprey ate the trout that were there originally.  The lamprey got in from the ocean when the Welland canal was opened.  The trout ate the ale wife.  With the decline of the trout, the ale wife population exploded.   Since they had a cyclical life like salmon, there were major dye-outs of alewifes.   The salmon were introduced to control the alewife population.  They now live entirely in fresh water.   Buckthorn was originally brought to the United States by landscaping companies.   It was a wonderful plant because it was hardy, green for much of the year (first to get leaves in the spring and last to lose them in the fall).   In addition it was pest resistance and the plants were easily propogated through the feces of birds.  How did these traits contribute to it becoming a problem as an invasive species?

Answer:  Since it was green both early and late in the year, it had an advantage over other plants as it's season for photosynthesis was longer.   It had no natural predators and when birds did eat the berries, it gave them diarrhea.   This helped with seed dispersal.  Therefore buckthorn is currently out-competing many of Minnesota's native plants.


Struggling Learners 

Struggling and At-Risk

Struggling and At-Risk students have needs above and beyond students with learning disabilities.   Often their family support system is less than optimal.   Building relationships with these students can be vital to their success.   Field experiences in which they have one-on-one time with the teachers or in small groups can be especially effective for these students.   Opportunities such as over-night field experiences or bus trips (although expensive) can be incredible learning opportunities.  Battling an invasive species and/or doing population studies of native species can provide positive ownership and authentic learning.  The environment offers an opportunity for these experiences that can be seldom replicated inside a tradition classroom.

English Language Learners 

For ELL students, the connection of vocabulary to real life situations can be especially important.   Taking children out into the field in places such as the school yard or more formally Environmental centers can be particularly effective strategies for teaching both biology and language.  Training which is designed especially for ELL students can be done with a focus on both the environment and language acquisition through the use of observation, scientific experimentation,  art and journaling.

Extending the Learning 

Students can research ecosystems that have been changed by human disturbances around the US or the world.

Students can conduct research on the environmental impact on a housing development, road construction, industry in their community and report to the city government.

Students can become a part of a data collection for an invasive species in their community.

Field work opportunities can be quite effective.  Summer opportunities with the Department of Natural Resources, projects involving local habitat development and projects developed to improve some aspect of invasive exotic impacts can be very effect methods for authentic learning.  Often times these can be tied to other areas of a students life such as the attainment of "eagle scout" status in boy scouts.

For highly computer literate students, they can write their own program analyzing the impact of an ecological problem and probable solutions.  Example:  What is the ideal balance of buckthorn erradication to control the problem and still maintain cost, energy and practical maintance on the part of the managers.  As different scenarios are entered, the program calculates the efficiency and practicality of the solution.


Students research the Native American perspective about the environment. One example is to research the plants that were present in Minnesota when the Native Americans were gathering food.    How does this compare to the plants we have today.   As an expansion this can become a project on prairie restoration or native plant propagation with an emphasis on how it has changed in the past several hundred years.  

Special Education 

For vocabulary have students use the Frayer model

Use Case Studies concerning environmental issues.  Students make T charts of the causes and effects.


Classroom Observation 


If observing a lesson on this standard what might they expect to see.

Students working outdoors, or with bottle ecosystems, would be  writing observations and sketching in their notebooks. In the classroom, students will compile class data and discussing how the site is changing.  Students would be researching Minnesota invasive species (or their local community, making brochures to inform the public of how to stop the spread in their community. Students organizing and participating in a community clean up of invasive plants such as buckthorn.


Parents can be encouraged to spend time with their children outside hiking, snowshoeing, camping.   These experiences foster awareness, knowledge and respect for environmental problems for all concerned.

Parents and grandparents can share their memories and skills related to working with the environment..

Parents can include students in their gardening and landscape designs.   They can plan gardens with native grasses and heritage plants.   They can consider the impact of adding non-natives to their landscaping and avoid doing so when they can.

Families can discuss their "ecological footprint" and ways they can reduce their impact on the environment.