PRISM Magazine On-Line  -  January 2000
Teaching Toolbox
Back To The Future

By Henry Petroski

Examining ordinary objects can give today's technologically savvy students the grounding in engineering that earlier generations got from tinkering with toys.

Illustration By Phil FosterIn a recent column in American Scientist magazine, I reported on a survey of business leaders who had begun their careers as engineers. The survey found that many of these captains of industry had fond memories of childhood play that centered around chemistry sets and construction toys, including Lincoln Logs, Tinker Toys, and Erector Sets. The executives also recalled that they were very curious about the way things worked, and as children they had engaged in a good deal of disassembling and reassembling of kitchen appliances, bicycles, and automobiles.

The response to that column was as great as that to any of the fifty-odd columns I have written to date. Engineers of all kinds contacted me to say how familiar the stories sounded to them and how they lamented the fact that students today do not have hands-on experience with construction toys or household appliances. The computer has put a screen between our students and the artifacts they are supposed to be learning to recognize, draw, analyze, design, and manufacture. It has fallen upon educators to devise new pedagogical tactics to overcome the tactile, visual, and verbal deficiencies that students now bring to the engineering classroom. I have three suggestions for remedying these deficiencies.

One way we can work with artifactually-deprived students is to bring physical examples to the classroom at every opportunity. It is best for the instructor to use artifacts related to his or her passion, hobby, or specialty, because it is these objects that the instructor is most likely to understand and be excited about in a way beyond their physical attributes and mechanical workings.

The mechanical engineer who works on antique cars in his spare time misses an opportunity to engage his students if he leaves discarded parts scattered around the garage floor instead of placing them on classroom desks. The electrical engineer who collects ancient (i.e., decades-old) electronic calculators misses an opportunity to demonstrate Moore's Law to her students if she does not ground it in artifacts. She can introduce the law—which states that every 18 months the density of transistors on integrated circuits, and thus the processing speed of computers, doubles—not just by drawing a graph on the blackboard but also by passing some of the data points around for the students to marvel at. Which one of them would not be fascinated by actually weighing in their hands one of the original Texas Instruments calculators that sold for hundreds of dollars against a credit-card calculator that is given away free today?

My second recommendation is that we bring to the classroom not only actual artifacts for show and tell demonstrations but also the simplest of objects to serve as inexpensive experimental apparatus demonstrating the concepts, principles, and phenomena we are teaching in our courses. In a statics or strength of materials class, for example, simple paper clip experiments can make many ideas more concrete and clear to students, including action-reaction, equilibrium, elasticity, plasticity, friction, three-dimensional deformation, bending, torsion, combined stress, and fatigue. The list is limited only by the instructor's imagination.

In an introductory engineering class, the paper clip can serve as a design project. In a course on product design, it can serve as a case study. Aesthetics, economics, environmental impact, ethics, failure, history, human factors, industrial design, manufacturing tolerances, marketing, materials, metal forming, packaging, product liability, quality control, reliability, safety, and a host of other topics can be discussed in the context of the paper clip, its manufacture, and its use.

Other common objects that I have had great success with are the pencil and the aluminum can. I have passed around a box of new pencils so that all students could have the same product in their hands, and not incidentally so that I could be confident in my predictions of how the pencil would behave when flexed or broken.

On days when I want to use the aluminum can in desk-top experiments, I place a picnic cooler full of cans near the front of the room, so that the whole class can enjoy discovering new things about an object they had so often held and used but not really seen, let alone appreciated its engineering design.

Years after such classes, students have brought me beverage cans and containers they have come across on trips and have excitedly pointed out to me some new design detail or curiosity of its manufacture. They have similarly sent me odd paper clips, exotic pencils, and newspaper clippings galore about artifacts of all kinds. This is, of course, exactly the desired effect—to get students who once had not given a second thought to the object in their hand to think like engineers and see every artifact as a joy to behold and as a potential source of a new engineering experience.

The third thing I would recommend so that engineering instructors can take every opportunity to give their students hands-on experiences is to have a supply cabinet in or near every classroom. In this cabinet there should be boxes of paper clips, pencils, chalk, rubber bands, index cards, reams of paper, and whatever else engineering instructors can think of that might give their students the opportunity to touch and feel the forces, textures, springiness, flexibility, rigidity, brittleness, or ductility of real things made of real materials. The cabinet should be accessible to all instructors in the department and should be constantly replenished by an appointed individual. The cost of providing this accessibility to the apparatus for desk-top experimentation in the classroom is minuscule compared with what it takes to set up and maintain a computer laboratory. Therefore, cost cannot be a real impediment to any department chairman or dean interested in giving students experiences that they have not brought from their childhood.

Hands-on experiences are not intended to replace those to be gotten in a computer laboratory or theory-based course. They are intended to supplement theoretical and computational experiences with those that are essential for fully understanding the import of the results of theoretical and computational analysis. Everything in engineering is in service to design, but no matter how complex a product of design an engineering student will encounter in his or her career, it will never be any less understandable or comprehensible for the student's having felt the spring of a paper clip or the flimsiness of an empty aluminum can. These simple experiences can be the foundations upon which engineering students born in the computer age will be better able to comprehend the devices of the future and rise to the challenges of leadership in the new millennium.


    Henry Petroski is Aleksandar S. Vesic Professor of Civil Engineering at Duke University,
    where he also chairs the department of civil and environmental engineering.
    He is the author of numerous books on engineering and design,
    including his most recent,
    The Book on the Bookshelf.

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