(Taken from pgs. 179-182 of Rieber, L. P. (1994). Computers, graphics, and learning. Madison, WI: Brown & Benchmark.)
Here's a simple example which may help you to understand the important principles and assumptions of rapid prototyping (RP). As Tripp & Bichelmeyer (1990) point out, RP has been a common tool for designers and engineers in many other fields, such as the aerospace industry. Fittingly, this example uses an everyday understanding of a complicated system - aeronautics - in the context of a universal experience (I hope) - building a paper airplane. The intent is to use this example as an analogy to instructional systems. If possible, find someone to do this project with you (I suggest a child). As you do it, get in the habit of expressing whatever thoughts are on your mind at the time.
Take a 8 1/2" X 11" sheet of paper and, without doing any "research," make a paper airplane. Go ahead and try it out. How well does it fly? Not so good? What should you do, start over? Resist this temptation at first, and, instead, try to make some modifications to your plane that you think will help it fly better. For example, based on your personal theory of "flight," fold the back edges of the wings either up or down slightly. Try flying your plane again. How much a difference does this little modification make? Continue to make additional minor modifications. Go with your feelings and intuitions. Make modification after modification and test lots of hypotheses regarding what you think should improve the plane's design. Maybe get paper clips and pennies to see if adding weight helps or hurts. You'll probably discover many important principles of flight as well as the boundaries and limits to these principles. Spend at least 10 minutes in this "experimental phase," still only using the first plane you constructed.
Now, stop for a moment to pause and reflect on what you just experienced and what you think you now know about the design of a paper airplane. Reflect on the meaning and importance of the design and development cycle and how important your test flights are to understanding if your design hypotheses are worth pursuing further. How many throws does it take to test one design hypothesis - one, two, five, ten? Consider the simple and straightforward feedback that each toss give you. How many total flights have you made? You probably lost count.
Take another sheet of paper and do it again. See if this next attempt begins with a better or more refined design. Are there things you will immediately do differently as you begin to test this plane? Unfortunately, you have probably been testing your plane very subjectively up to this point. That is, you know a good flight when you see it, but you probably have not, as yet, expressed in some objective way what you feel are the characteristics of a good flight. Therefore, let's give some serious thought to the testing of this plane. What criteria should you use to judge the effectiveness of the plane's design? Most people usually use distance as an important measure, perhaps followed by accuracy. Try to make your testing as "objective" as possible. Set up a testing environment which builds in your criteria and start collecting data. Let's focus on distance and accuracy. Clear a "flight path" in the room where you are working (or better yet, find an unobstructed hallway). Choose a starting line. Throw your plane and keep track of the number of times your plane lands within a certain path (to test for accuracy) and also how far your plane travels (to test for distance). Keep a careful record and study your "data." Calculate some statistics. What is the average distance? What is the percent of accurate flights? Get some other people involved and have contests. See who can design the "best" plane.
After you've arrived at the "winning" design for a paper plane, do something that is both unnerving and disconcerting: take another sheet of paper, crumble it up into a ball, and see how well this "design" fares under the testing environment you've devised. My guess is that this "plane" does as well or better for both distance and, especially, accuracy than the planes you've designed up to this point. Why? There are several reasons. Distance and accuracy, though important, do not capture other important elements of aerodynamics related to concepts such as "gliding ability" or "lift." You also probably did not control for the amount of force allowed for each throw. Add these to your criteria and see what happens. Some designs seem better able to "ride on" or glide in the air.
How similar are the designs of all the people involved? Unless there is an individual in the group who either is very creative or has an interest in paper planes and knows other designs due to past experiences, chances are the planes are almost identical in terms of their fundamental design. The first design most people come up with usually resembles something like this:
See below for examples of other "radical" designs (insert a graphic of a "flying wing" and a "ring wing" plane on a later page). Build them, test them, and compare their results to those you've created.
What is this little activity supposed to teach us about rapid prototyping of instructional materials? First, notice that design and development were intertwined and interdependent. Did you plan out your design by, say, drawing it out on a separate sheet of paper? Of course not. Not only is it a rather silly thing to do, it's also very difficult. Try it sometime. How do you represent the procedural nature of the design? How do you represent hidden folds or the strategic tearing of paper. In fact, it is much simpler to "show" your design in the completed model. Similarly, it is important to consider the "gulf" between design and development of instructional materials. Even in traditional instructional approaches, design and development are expected to provide important feedback loops to the other. You are expected to learn about design through the testing of early prototypes. In other words, instruction is meant to be improved over a succession of design and development cycles. This is the role of formative evaluation at the lesson level. Unfortunately, all too often there is too great a gulf between design and development so that by the time the first draft materials are developed, there is already too great an investment in the original design. There is a high risk early on to growing complacent and accepting and committing to inferior designs. RP assumes that you will learn much, if not most, about your design only through rapid turn-over of design, development and evaluation.
Second, consider the "medium" in which you have been working - paper. As Tripp & Bichelmeyer (1990) note, RP assumes that the medium satisfies the attributes of modularity and plasticity. Paper allows you to fold, bend, and shape the plane in a variety of ways. It allows you to change small, but important features of the plane's form quickly and easily (remember the bending of the back of the wings). Adding and subtracting elements, such as weight via paper clips and pennies, can be tried after the basic design is finalized. How well would other media work? Try using light and then heavy cardboard. Now try using modeling clay. You might as well throw a rock. The lesson here is that the medium must still be appropriate for the task. Paper, unlike clay, has some inherent characteristics which are appropriate for flight: light, strong, holds shape, long and flat while still rigid enough to "catch" and "ride" the air. Similarly, one cannot choose an instructional medium arbitrarily. The medium must still be appropriate for the activity. The virtues of RP, therefore, cannot be realized in every instructional medium, at least not at the same implementation level.
As you built the plane you probably felt the urge to try it out as soon as possible. Although you were probably careful as you made your folds, you probably did not want to spend more than a few minutes designing and constructing your plane. That's easy to understand, because the fun is in flying the plane, not building it. You also know from the start that the value and interest in the project is in the act of flying, not in the act of folding. Although one could make a case about the aesthetic appeal of the plane (as in the case of building a store-bought plastic model kit), most people rarely use aesthetics as a way to judge their paper plane. Similarly, the value and interest in an instructional design is in its implementation. You learn about the value of the design only by developing it and trying it out. Did you expect your plane to fly perfectly the first time you threw it? Perhaps you had high expectations at first, but you probably discovered soon that the plane would never fly as well as you first thought. Similarly, the only way to get a realistic analysis of the completeness, appropriateness, and limits of the goals of an instructional design, and subsequently, its effectiveness, is in the actual context of its use.
Consider how you arrived at your first design. The traditional model for a paper airplane is usually the only one with which most people experiment. Thereafter, it is usually very difficult to come up with truly alternative, creative designs. The same probably holds true for many instructional designers. They tend to think of instruction in only a limited number of ways. The traditional paper plane design might be analogous to a traditional application of Gagné's events of instruction. Once you have formulated your own sense of what instructional design is or should be (such as "first present information to students, and then you have them practice it"), it can be difficult to consider alternatives. Although one may make many minor adjustments (such as trying different questioning strategies), the basic fundamental design remains the same. RP allows (encourages) you to design, develop, and compare seemingly opposite designs.
The ways in which you tested the paper plane also offer very important lessons for instructional design. Feedback from testing is only valid if you are gathering appropriate kinds of information and interpreting it in appropriate ways. Distance and accuracy seem like obvious data to collect - until you compare the performance of a paper ball (especially one filled with paper clips). When testing instructional designs, one needs to be sure that the tests properly reflect the objectives. RP goes further to help designers to fine tune their initial objectives and to determine others. Too often, we only interested in "performance" data, like scores on a posttest, and fail to consider other sources of information, such as a student's motivation to participate and persist in an activity. It might be argued that almost any design will produce results if we somehow require (or force) students to comply, such as with external incentives such as grades, much like the paper ball being thrown as hard as possible simply to satisfy the goals of distance and accuracy. Perhaps the lesson for instructional designers is to be on a constant vigil for information which may provide useful insights to improve the instruction. In addition, it is important to remain open to consider information from a wide variety of sources. The best designs for a paper plane take advantage of the plane gliding through air with only the slightest momentum. So too, the best instructional designs usually work by intrinsically motivating the student to go as far as they can with but the slightest prompting or coaxing.
Reference
Tripp, S., & Bichelmeyer, B. (1990). Rapid prototyping: An alternative instructional design strategy. Educational Technology Research & Development, 38(1), 31-44.
Here are some other, more radical paper plane designs as referred to above. The design on the left is called a "flying wing" and when properly constructed is a superb glider. The paper plane on the right is based on the "ring wing" design by Georgia Allison of the NASA Langley Research Center. This latter design is supposedly only half the weight of a conventional airplane, but carries the same payload.