Keywords: biodegradable wastes, dissolved oxygen, microbes; Lesson Plan Grade Level: seventh through ninth grade; Total Time Required for Lesson: 90-minute continuous blocks; Setting: classroom laboratory

Goals for the Lesson

  • Students will be able to evaluate the relationship between biodegradable waste and dissolved oxygen in water.
  • Students will be able to explain the relationship between oxygen levels, bacteria and the breakdown of organic matter using an indicator solution.

Materials Needed

  • lab activity worksheet
  • beakers
  • dry yeast
  • graduated cylinders
  • test tubes and test tube racks
  • stirring sticks
  • pipets
  • methylene blue solution
  • masking tape
  • marking pens/pencils
  • milk
  • water

State Standards Addressed: E & E Standards: Watersheds and Wetlands (4.1.7 A); Earth Science Standards: Explain the Behavior and Impact of the Earth's Water Systems (3.5.7 D); Assess the Value of Water As a Resource (3.5.10 D)

Teaching Model: Lecture/Discussion, Cooperative Learning

Subjects Covered: biology, environment & ecology

Topics: aquatic ecosystems, water quality, abiotic & biotic factors


  1. Give each student a copy of the lab activity and read over the purpose and discuss the general concept of the lab with the class.
  2. Break students into lab groups and have them complete the pre-lab activities using their textbooks and any other available references.
  3. When the groups have finished the pre-lab activities, discuss the answers to the questions with the class. Review and discuss the different hypotheses that the class has constructed and have groups make modifications or rewrite their hypothesis if necessary.
  4. Review lab procedures with class and demonstrate any specific lab techniques. It is a good idea to show an example of a test tube before and after the experiment so students know what they are watching for. Assign lab roles such as set up, facilitator, recorder, and clean up, if so desired, and then allow groups to begin the lab activity.
  5. Monitor groups progress and facilitate as needed.
  6. When each group finishes the activity they should clean up their lab station and work on the conclusion questions.


  • Students will analyze their results and complete the conclusion questions.
  • Final class discussion and evaluation of group results.


Hach Company (1991). Experiment 2: Effects of Biodegradable Waste on Dissolved Oxygen.


Kristina Rogers, Loyalsock Township High School