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Problem-Based Learning: UV Menace

Scenario and Teacher Pages by NASA's Exploring the Environment Team - Starting Point Page by Rebecca Teed (SERC)
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This material is replicated on a number of sites as part of the SERC Pedagogic Service Project
Initial Publication Date: November 16, 2006 | Reviewed: October 22, 2012


Logo element from Exploring the Environment

A problem statement is a student-centered challenge requiring cooperative effort. For this project, the student group needs to assess the causes, effects, and possible solutions to ozone depletion. The student team:

  1. Brainstorms about their pre-existing knowledge and assembles a summary of what they (collectively) already know (some of it may be outdated or incorrect) and where they learned that knowledge.
  2. Works out what they need to know to go further (this may include checking pre-existing knowledge)
  3. Divides the knowledge needed to move on into discrete questions or areas of expertise (such as hydrosphere, biosphere, lithosphere, and atmosphere) and assign different pieces to different team members.
  4. Individual team members head for the library and search the Internet for information about their aspect of the problem. They need to be in contact with their teammates in case they find something relevant to another part of the problem.
  5. Once research is done (or time runs out), the individuals write up their chapters and gather with their team to edit them for correctness and consistency and to write a collective introduction and conclusion.

The instructor should make sure all of the students have a decent background in basic atmospheric chemistry and the effects of ultraviolet radiation. A lecture may be necessary. Students may also need help with chasing down sources and keeping their groups on track.

Used this activity? Share your experiences and modifications

Learning Goals

As they work on this project, students will:
  • Analyze a problem in terms of what they already know and what they need to learn
  • Do research independently but work with a team to divide up tasks and synthesize findings
  • Learn about ozone depletion, a serious environmental problem
  • Think about interactions within the Earth system that can magnify or reduce a problem like ozone depletion

Context for Use

This project is for an Earth system or environmental science course and will probably take three class periods over a couple of weeks.

Tropospheric ozone above Indonesia caused by smog
  • Allow a class period to introduce the problem and to make sure that students understand the basics
  • Another class period for the students to assemble their prior knowledge
  • Give the teams a couple of weeks for their research, to write individual chapters, and to post them to a central bulletin board (or copy them) for their teammates to read.
  • During the last class meeting, the team does the last edits on the chapters, and writes a rough draft of the introduction and conclusion.

Teaching Materials

The Learning Cycle

The project starts with students doing assessing their prior knowledge of the the problem. This serves a lot of purposes.

  • It gives the instructor an idea of how much background briefing the team needs.
  • This enables the team to realize how far along they already are, encouraging them, and when two teammates differ in what they know, it encourages them to critically evaluate the reasons for those differences.
  • It helps the team move on its own to the next step: what needs to be known? Additionally, the team may divide questions up based on who is best prepared to tackle a particular aspect of the problem.

Independent research allows the team members to construct their own knowledge and synthesis of the chapters lets them learn from one another. Encouraging them to edit one another's work furthers learning and critical thinking. The introduction and conclusion allows the group to reflect on what they have learned and to assess its own progress.

The Teams

I've found teams of four students to have the fewest problems.

Ozone Hole over Antarctica from TOMS data Oct. 1999
  • Interdependence is fostered by the breadth of the project and by the shared final project, a problem statement.
  • Interaction is essential, which is why I recommend working together in class time. An online bulletin board where teammates can leave each other messages is also useful. I have also used these projects in online courses, but they require a great deal of communication between students.
  • Individual accountability: This is a group project, but if you have a copy of the initial work plan delegating various questions to specific team members, you will know if one person performs poorly in their share of the final project and can intervene, grade that person separately, and if necessary, remove them from the team for the next project. A peer assessment component may also be helpful.
  • Editing and synthesis in particular will require good interpersonal skills. A brief discussion of how to do good peer review at the start of the project might be helpful.
  • Group processing takes place at the last meeting, when the students synthesize what they have learned. You can encourage it further by asking students to include a section in the conclusion on aspects of the problem that they still don't understand.

The Scenario

The UV Menace ( This site may be offline. ) subsite is part of NASA's Exploring the Environment (more info) site which has an extensive collection of scenarios suitable for problem-based learning. It includes brief sections describing the problem in general, and its specific relationships to the hydrosphere, atmosphere, lithosphere, biosphere, and anthroposphere, plus a page on what remote sensing can tell us.

The Problem Statement

The final product can take the form of a paper, a presentation, or a web site.

  • I generally require a preliminary report first: describing what the group knows, defining the information that they still need, and delegating various questions to specific team members.
  • Then they compose a research paper (often 16-20 pages!!) with an introduction laying out the problem written by the group and finished by the editor, topical chapters by each member of the team, and a conclusion advising one or more responses to the problem by the community affected either as a chapter or, better, by the group.

Teaching Notes and Tips

Four things I found to make problem-based learning run more smoothly:
  • Give the students the rubric/grading standards ahead of time and discuss it with them to make sure they understand what is being asked of them.
  • One student is the editor: this person serves as an encourager and timekeeper throughout most of the project, keeping the rest of the team on track, and as the final writer of the introduction and conclusion. This responsibility rotates over the course of the term and could be split up.
  • Make sure that students understand the basics of this material beforehand. A similar exercise on global warming in my class was nearly derailed because none of the students understood the carbon cycle very well.
  • Have students at least proof-read and peer-review one another's chapters before starting the final synthesis. It improves the final product and reduces concerns that some team members are not working hard enough.


If you are designing your own rubric/grading standards for the problem statement, the assessment section of the Teacher Pages for Exploring the Environment ( This site may be offline. ) has detailed advice.

Specific rubrics from ESSEA Online Courses can be used to grade a two-part problem statement:

  • Problem Statement: week 1, mostly a work plan
  • Earth System Model: week 2, the full-fledged research paper

References and Resources

For more Problem-Based Learning advice, examples, and scenarios:
Meteor3 satellite equipped with ozone-measuring equipment
  • ESSEA Online Courses: 9-12 Earth System Science Course. This 16-week online graduate course for high school teachers is offered by colleges and universities across the United States as part of the NASA ESSEA Program (Earth System Science Education Alliance). The course is structured as a collaborative, Problem-Based Learning (PBL) experience. It is modeled so that teachers will learn to use science as inquiry from the student perspective and then be able to model this teaching approach in their own classrooms. Specifically, teachers will evolve their own knowledge about Earth systems science and their skills in thinking systemically about specific events; learn to develop strong arguments with hypotheses, assertions, and evidence; develop collaborative skills for knowledge building, argument building, and acting as a critical friend; and develop PBL experiences that will engage their students in using Earth systems science thinking. (more info)
  • Exploring the Environment. On-line, problem-based modules developed by NASA's Classroom of the Future for K-4, 5-8, and 9-12 teachers and students. Modules address events such as volcanoes, hurricanes, dinosaur extinction theories, deforestation, endangered species, and global climate change. The use of NASA remote-sensing images is a feature of the site - along with a tutorial about how to analyze Landsat images with NIH Image. (more info)
  • SCORE: Problem Based Learning. General advice on what PBL is and how it works, along with references and links to more such resources. ( This site is likely no longer available. )
  • The National Center for Case Study Teaching in Science. This resource offers a collection of case studies for use in undergraduate science classrooms. It provides a sample of the recent attempts to introduce the method into the science classroom and a glimpse of its potential as seen through the eyes of some of its most ardent advocates. Designed to humanize science and to illustrate scientific methodology and values, the cases also develop students' skills in group learning, speaking, and critical thinking. The cases are organized into topics that present issues in chemistry, ecology, and physics and engineering as well as medicine and health, molecular biology, and teaching scenarios. The site also references videotapes, articles, books, bibliographies, and case study literature. ( This site may be offline. )
  • Using Investigative Cases
    Starting Point Module that explains the Bioquest model for PBL with detailed environmental examples