Eric Blinder- A Dynamic Ecosystem

Lesson Plans for  High School Biology
Time Needed:  2 periods of 110 minutes each

California Content Standards Addressed:

6. Stability in an ecosystem is a balance between competing effects. As a basis for understanding this concept:  a.Students know biodiversity is the sum total of different kinds of organisms and is affected by alterations of habitats.  b.Students know how to analyze changes in an ecosystem resulting from changes in climate, human activity, introduction of nonnative species, or changes in population size.    d. Students know how water, carbon, and nitrogen cycle between abiotic resources and organic matter in the ecosystem and how oxygen cycles through photosynthesis and respiration.

Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other four strands, students should develop their own questions and perform investigations. Students will:  a.Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data.  b.Identify and communicate sources of unavoidable experimental error.  c. Identify possible reasons for inconsistent results, such as sources of error or uncontrolled conditions.  d. Formulate explanations by using logic and evidence.


  • colored pencils (for each group)
  • Student Handouts  (attachment at bottom of page)
    • "Lakeville Map"
    • Data Tabe #1
    • Procedure and Background Information
    • Program Cost, Benefits, and Drawbacks


  • Students read the introduction to the activity and background information.
  • Perform a PO4 test as an example using tap water or fish tank water.
  • Using the colored pencils, students translate the data compiled in Table #1 to the corresponding test sites located on the map of Lakeville.
  • Using the different colors, students will create a visual representation of where the majority of phosphorus contamination is coming from in Lakeville.
  • Students read the "Scientific Report".
  • Based on the map of Lakeville and the "Scientific Report", students should create a rough plan for how to handle the phosphorus contamination in Lakeville.  
  • Given a budget of $500,000 to deal with the phosphorus issues in the lake, students take on the role of city council members and develop a cost effective, long term plan for Lakeville.  Students need to use the "Program Costs, Benefits, and Drawbacks" sheet provided.
  • Students compare the different plans created within their group.  As a group, students select the best plans or aspects of each others plans and create a final product.
  • Students will assess the effectiveness of their plans by completing the Analysis questions at the end of the student handout.
  • Each group will present their plans to the class as members of the city council.

Student Prior Knowledge

  • Students have studied evolution and understand that humans have a great impact on their environment.
  • Students have written and discussed the concept of "trade-offs" or opportunity costs, and have related that concept to their own lives and communities.
  • Students have shown understanding of the concept that there are limited resources available for humans and that the balance of nature may be compromised in order to fill certain needs.
  • Students have observed pollution and understand its negative consequences.


This is a great activity for students of all skill levels and abilities.  The students take on a role of responsibility with this activity and are forced to make informed decisions that effect other people's lives.  The students benefit from the aspect of the activity which requires them to locate the largest sources of phosphorus pollution in the lake because their results may reflect something other than their hypothesis.  Because of this, students will most likely need to change their original thoughts and solutions based on the data. 

Question and Answer

  1. How did you determine which plan will lead to the most sustainable and effective solution?   Answers will vary, this is a possible response-We looked at each plan and tried to decide which one fixed the phosphorus problem, but also had long term solutions to help prevent it from happening again. The plan we felt worked the best included building a new wastewater treatment plant, a car wash, an educational program about phosphorus and a community action program to label storm drains. We decided to use our remaining money for a community ad campaign to help get the word out about the car wash and the other programs. We think this is the most sustainable solution, but we know from that there might be other problems affecting the fish population.
  2. How could you measure the success of your plan if it was implemented in Lakeville?  What indicators would you use to determine if progress had been made?  What indicators would you use to determine if the program had been completely successful?   Answers will vary, this is a possible response- In order to measure the success of our plan we would test the water for phosphorus at one month intervals after our plan was put into effect. We would also test the water once a year after that. Our indicators of progress would be the results of those tests, and the results of the education programs. We would know progress had been made if the water was less contaminated, and the community was consistently using the car wash and cleaning up after their pets because of what the education programs taught them. We would consider the program successful if the water tests came back clean for ten years.
  3. What evidence form the indicators would mean the program was successful or not successful?   Answer-We know from the scientific report that phosphorus is dangerous to lake organisms at concentrations of 55 ppm or higher, and that it is lethal over 85 ppm. This means that before our cleanup anything that was red on the map had lethal levels of phosphorus and anything yellow or orange could cause problems. Because the main focus of our program is to make sure the fish die offs and algal blooms are greatly reduced, we would want all of our tests to indicate that the concentrations of phosphorus in the water were at least under 55 ppm. The evidence we would look at would be the results from our water testing done after the programs started. If any of the results showed phosphorus concentrations over 55 ppm it would mean the program was not successful. If all of the results showed levels under 55 ppm, our program would have been successful. However, if the tests were under 55 ppm but were still high or close to that number, we might want to rethink our indicators and see if we wanted to make them more strict.

Applications to Everyday Life

This activity allows students to analyze data surrounding a real world issue.  As residents of Los Angeles, these students are well aware of the reality of the problems associated with pollution.  This activity encourages students to take a scientific, analytical approach to problem solving issues within the community.  As a result of this activity, students will have a greater understanding of the thought processes necessary to make a decision that may effect many people.

Norman Herr,
Feb 15, 2011, 8:19 AM