Building Bridges

By Evy Potochny

Scientific illiteracy abounds in America. One recent poll, funded by the National Science Foundation, found that fewer than half those interviewed knew that the Earth takes one year to orbit the Sun.

Unfortunately, grade-school teachers are not immune. And if teachers can’t make sense of basic scientific concepts — if they can’t “integrate them into their own understanding,” as Vincent Lunetta, a Penn State professor of curriculum and instruction, puts it — then it is next to impossible for their pupils to do so.

Notes Akhlesh Lakhtakia, a professor of engineering science and mechanics, “The kind of students I often teach, although bright, don’t know how to analyze, to break a job or task into several parts and figure out how it works.” These skills, he adds, need to be taught in grade school. And by using concrete examples. “If we want to teach children analytical skills, we should not teach science through abstract notions. That does not inspire children.”

Two years ago, Lunetta and Lakhtakia got together to work on improving elementary science instruction. SciEd 497: The Fundamentals of Science, Technology, and Engineering Design was born.

The “fundamentals” include the stability of shapes, mechanisms of simple machines, and conservation of energy. Joe Taylor, the graduate student who teaches the class, typically uses his students’ preconceptions of scientific principles — force, motion, and electricity — as the basis for customized instruction. Students about to study levers, for example, are asked to bring in household gadgets. These — bottle openers, scissors, staplers — are held up for discussion. Recognizing science in everyday objects, he says, is the first step to understanding it.

The students then morph into engineers in a hypothetical construction firm, working in groups of three or four. Their task is to design a bridge suited for car and pedestrian traffic across a waterway. Computer simulation software lets the students select parameters — length, height, and style of bridge — and test their designs. If an animated truck makes its way safely across the bridge, the design is sound. If not, the bridge collapses, sending the truck toppling into the water.

Once a design is agreed upon, the group goes to work with Lego and K’NEX blocks to build a scale model across a two-foot gorge between rows of desks. The finished bridges, says Taylor, can be remarkably different, helping students realize that a single problem can often have multiple solutions.

Each “firm” then prepares a presentation — including digital photos — and presents it to a “town council” made up of Lunetta, Lakhtakia, and other guests. Their goal is to convince the council that their bridge is both cost-effective and structurally sound.

Next, the same bridges must be substantially renovated, so that they can be raised or lowered for the passage of tall ships. Here, Taylor says, students learn about integrating basic machine systems — wheels and axles, pulleys and gears — and determine how the resulting complex machine can best perform the task. The last segment of the course introduces electrical circuits: the students add buzzers and lights to signal when the bridge is in use.

Fatih Tasar, a graduate student in science education, has studied how the students’ initial scientific conceptions change over the course of the semester. Before a topic was covered in class, Tasar had students make word associations. For the concept of acceleration, he writes, one student chose “rate of change of velocity.” Often, Tasar says, a student will memorize a scientific formula, i.e., acceleration = rate of change of velocity, without actually understanding it.

During the course, Tasar says, the students’ understanding of abstract concepts evolved. One student, whose last physics class had been in seventh grade, initially understood acceleration as “whether or not a person is pushing harder” on an object. To get across the correct meaning, Tasar asked the student to think of a growing population. If the rate of increase from year to year drops from two percent to one percent, the rate of acceleration is decreasing. After that explanation, he says, “It began to make sense to her.” Later in the semester, however, the same student again had difficulty explaining acceleration until prompted to remember the population analogy. Tasar concluded that while analogies can be helpful, long-held misconceptions are often hard to change.

Despite this resistance, Taylor adds, “What we’ve been hearing in end-of-semester interviews is a new confidence as science learners.”

“I feel very comfortable with teaching science now,” confirms one elementary-education student. “I feel as if I could handle almost any question my future students might ask about simple machines.”

“My roommate is an engineering major,” says another. “He couldn’t believe that I was analyzing these complex truss bridges. At first, he just wanted to show me how he would do the problem. But by the time we were done talking, he asked me to show him my way. It really made me feel proud of what I had learned.”

Joe Taylor is a Ph.D. student studying science education. M. Fatih Tasar completed his doctorate in science education in August 2000. Their advisers for this project were Vincent Lunetta, Ph.D., professor of education, College of Education, 166 Chambers Bldg., University Park, PA 16802; 814-865-2237; vnl@psu.edu; and Akhlesh Lakhtakia, Ph.D., professor of engineering science and mechanics, College of Engineering. SCIED/ENGR 497f has been supported by the NSF-funded program ECSEL (Engineering Coalition of Schools for Excellence in Education and Leadership). In September, the Science Education Program received the Provost’s Special Recognition Award from the University for this and other projects.