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Teaching Biology Through Problem-based Activities

Judith Williams


This long term, problem-based teaching unit was developed to address the issue of getting all students actively involved in the learning process at the beginning of the school year. The unit's activities emphasize inquiry-based learning as an ongoing process and include integrated science and math experiences. Using Wisconsin Fast Plants, students plant seeds and observe the complete life cycle of the organism during part 1 of the unit. Students experimentally research the effects of radiation on radish seed germination and seedling growth in part 2 with cobalt radiated seeds provided by the teacher and in part 3 with seeds exposed to ultraviolet radiation by the students. In part 4, students design, set-up and complete individual experiments determining the effects of different environmental pollutants on the Wisconsin Fast Plant seeds harvested during part 1 of the unit.


  • hands-on
  • inquiry
  • group/cooperative learning
  • individual performance
  • alternative assessment

  • Biology
  • Environmental Studies

  • To give students opportunities to develop skills in problem solving
  • scientific process skills
  • cooperative learning
  • critical and creative thinking
  • written, visual and oral communications

    All materials and directions needed to grow Wisconsin Fast Plants can be purchased from Carolina Supply Company. (Reminder: these plants require 24 hours of light banks for proper growing.)

    Irradiated seeds can be purchased from different biological supply companies. I have also had seeds irradiated for different time exposures with X-ray machines at local medical facilities. Other needed materials to germinate seeds will vary depending on student developed procedure. (Seeds I used were obtained from Kansas State University during a NSF workshop.)

    U-V light box can be purchased or can be hand constructed. ( Mine was home-made and was obtained from Kansas State University during a NSF workshop.)

    Other needed materials to germinate seeds will vary depending on student developed procedures.

    Other materials will vary depending on student designs of individual experiments.

    PART 1:

    The unit is implemented at the beginning of the school year with the problem "What kinds of changes occur in plants as they develop, mature and reproduce during their life cycle?" Students plant Wisconsin Fast Plant seeds in quads using the growing guidelines provided by Carolina Supply Company. During the next forty days, students observe the seeds germinate, plants grow and flower, and seed pods develop after pollination of flowers with students' bee sticks. Each student harvests and stores the seeds from his/her quad of plants. Throughout the project's duration, students keep personal logbooks to record all data. Data is mathematically analyzed to determine the percentage of seed germination and the mean numbers of flowers per plant, seed pods per plant and seeds per plant for each quad. Mean plant height is determined weekly during the project's duration. Students prepare tables of all students' data in order to compare and contrast individual and class results.

    PART 2:

    Students complete other activities to increase their content knowledge on organisms and to create an awareness of environmental problems as they began to question "What effects do pollutants have on living organisms?"

  • I pose a set of questions to the students.
  • What is radiation?
  • Can you name different types of radiation?
  • What are the differences between the types?
  • What about the effects of radiation--good or bad?
  • Do different types of radiation affect organisms differently?
  • Does one type of radiation affect different kinds of organisms differently?
  • Students research background information on radiation and share their knowledge with classmates. After discussing the questions, I introduce the new problem "What effect will exposure to different hours of cobalt radiation have on the germination and seedling growth of radish seeds?"

    Students work in small cooperative teams to develop a "class" procedure. The "class" procedure is completed by each team working with radish seeds that have been previously exposed to 2 hours, 4 hours, 8 hours, and 16 hours of cobalt radiation plus the control group. Teams record their observations, analyze class data, and reach conclusions.

    PART 3:

    Students identify environmental radiation problems that could be simulated and experimentally researched in the classroom. Working in small cooperative teams, they design and complete experiments using the U-V box in our room to test the effects of different exposure times of ultraviolet radiation on the germination and seedling growth of radish seeds. As students observe the effects of radiation on seed germination and seedling growth, they begin expressing an interest in knowing more about their environment.

    PART 4:

    Activity 1: (Class activity)

    Teacher states the class problem: "What effects will different environmental pollutants have on Wisconsin Fast Plants?" Working in small cooperative teams, students brainstorm environmental problems that could be simulated and experimentally researched in the classroom. Teams share their lists, and a master list of brain stormed problems is compiled.

    Activity 2: (Individual activity)

  • Select a problem from the list brain stormed in activity 1 or decide your own problem.
  • Research background knowledge on the pollutant using available resources in the classroom or in the media center. Make abstract summaries of all sources and include a bibliography.
  • Formulate a hypothesis.
  • Design a controlled experiment to test the effects of the simulated pollutant on the seeds harvested and stored from the first crop of Fast Plants in the fall.
  • Gather materials needed for the experiment using any available in the classroom or materials brought from home.
  • Set-up and complete experiment recording all observations in a dated logbook.
  • Analyze data and prepare table(s) and graph(s) of results.
  • Reach a conclusion.
  • Create a visual display of your choice (poster board, hypercard stack, video, table display, etc.) that includes the problem, hypothesis, materials and procedure, results including table(s) and graph(s), and conclusion.
  • Using the visual display, orally present your experimental research project to classmates during our "Classroom Share Day."

    Assess student performance using a problem-solving rubric. (I designed the rubric I used after reviewing other science rubrics.)

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