In a PBL course, the selection of appropriate problems is critical to the success of the course. The following is a list of the important characteristics of a good PBL problem.

1. An effective problem must first engage students' interest, and motivate them to probe for deeper understanding of the concepts being introduced. It should relate the subject to the real world, so that students have a stake in solving the problem. If at all possible, the problem should be placed in a context with which students are familiar.

2. Good problems require students to make decisions or judgments based on facts, information, logic and/or rationalization. Students should be required to justify all decisions and reasoning based on the principles being learned. Problems should require students to define what assumptions are needed (and why), what information is relevant, and/or what steps or procedures are required in order to solve the problem. Not all the information given in the problem should be relevant to a solution. And not all the information needed for a solution should be initially given to the student. For this reason, many PBL problems are designed with multiple stages, to be given to student groups one at a time, as they work through the problem.

3. Cooperation from all members of the student group will be necessary in order to effectively work through a good problem. The length and complexity of the problem or case must be controlled so that students realize that a "divide and conquer" effort will not be an effective problem-solving strategy. For example, a problem that consists of a series of straight-forward "end of chapter" questions will be divided by the group and assigned to individuals and then reassembled for the assignment submission. In this case, students end up learning less not more.

4. The initial questions on the first stage of a problem should be open-ended, based on previously learned knowledge, and/or controversial so that all students in the groups are initially drawn into a discussion of the topic. This strategy keeps the students functioning as a group, rather than encouraging them to work individually at the outset of the problem.

5. The content objectives of the course should be incorporated into the problems, connecting previous knowledge to new concepts, and connecting new knowledge to concepts in other courses and/or disciplines.

6. The problem's questions should challenge students to develop higher order thinking skills, moving them beyond Bloom's (1956) lower cognitive levels of knowledge and comprehension to the higher Bloom levels, where they analyze, synthesize and evaluate.

Sources of Good Ideas for Problems
So now that we know what makes a good problem for use in PBL - how can you write one? Some faculty use video-clips, stories, novels, articles in the popular press, and research papers as a basis of a problem. Frequently, faculty members use a typical textbook problem, and rewrite it as an open-ended, real world problem. You might think of following the following steps to writing a PBL problem:

Step 1 Choose a central idea, concept or principle that you always teach in your course. Then, think of a typical end-of-chapter problem, assignment, or homework that you tend to assign to students when you teach that concept. List the learning objectives you want students to meet when they work through the problem.

Step 2 Think of a real-world context for the concept you've chosen. At this point, you could think of a story-telling aspect to an end-of-chapter problem. This adds some motivation for students to solve the problem, and it requires students to go beyond simple "plug-and-chug" in order to solve it. Look at magazines, newspapers, articles for ideas on the "story-line". You might think of talking to professional in the field for ideas of realistic applications of the concept you are teaching.

Stage 3 At this point, you want to flesh out the problem by asking yourself some of these questions:

• What will the first page look like? What open-ended questions can I ask?
• How will you structure the problem?
• How long will the problem be? How many class periods will it take to complete?
• Will you give students information in subsequent pages as they work through the problem?
• What resources will students need?
• What end-product will students produce at the completion of the problem?

Usually PBL problems are multi-stage or multi-page and may take student groups a week or more to complete. Not all the information needed to solve the problem is given in the problem, or chapter, or perhaps even in the textbook. Students will need to do some research, discover new material, arrive at judgments and decisions based on the information learned. The problem may have more than one acceptable answer, based on the assumptions students make.

Step 4 Write a teacher guide detailing how you plan to use the problem in your course. If you are using a combination of mini-lectures, whole class discussion, small group work with groups regularly reporting out to the whole class, you will want to indicate how you plan to cycle through the pages of the problem interspersing the various modes of learning.