A Web-based instructional module for teaching middle school students engineering design with simple machines

Journal of Engineering Education, Oct 1998 by McKenna, Ann, Agogino, Alice

Some of the off-line activities included building levers with LEGOSTM. The students used the LEGOM models to investigate what happens when the pivot point is physically changed or the bar is lengthened. These hands-on activities were accompanied by the online lever web assignments. The students ran the lever simulation, as shown in figure 3, and recorded the results obtained for the four different loads at three different fulcrum positions. These results were then entered into the plotting program, shown in figure 4, to produce a graph. The students compared the results obtained from their physical experiments with the LEGOSTM to the results obtained from the computer simulations. Finally, the students were given a choice of completing one of three different LEGOM projects that require the design of an original device that uses the principle of a lever.

The off-line and on-line activities facilitate development of the students' understanding of mechanical advantage for the lever. As the students worked through these various activities they entered comments and results to the Share Your Findings Page. Some of the students' comments are given below.

Tom*: "The closer the fulcrum is to the load, the less effort force required to move the load. But it also increases the distances needed to move the lever. In other words, the closer the fulcrum is to the load, the less force and more distance."

Rita: "My understanding of how levers work has increased. I learned about how much effort it takes to lift certain objects. I also learned about how the effort changes when the fulcrum distance is moved."

Drew: "I found that there are three main parts of a lever that define how and why a lever will act as it will. These parts are the effort, fulcrum, and load. I found that simple machines are put together to make more complex, larger machines. The main point of a small machine is to complete a simple task"

Vicki: "What I didn't know before was that the closer the load is to the lever, the lighter the effort will be. Simple machines are a little more interesting now since they are now much easier to understand."

Ron: "In the classes on mechanical engineering I learned a lot. I had never known much about simple machines but I learned a lot about them, especially the lever. Most of the facts I learned I had never heard before. It also was an activity that used a lot more math than I thought it would."

These comments indicate that the students abstracted the principle of the lever and recognized a relationship between the force (effort) needed and the position of the fulcrum point. The comments suggest that the simple machines module was successful in accomplishing the intended cognitive goals of developing concepts about simple machines and encouraging self-reflection.

In addition to facilitating an understanding of the principle of the lever, the activities were structured to provide students the opportunity to develop and practice engineering problem solving skills. After the students investigated the principle of the lever with the computer simulations and LEGO' building, they used their results to inform the solution of their design projects. The students engaged in the activities of simulating and prototyping as they built their design projects with the LEGOST. The combination of these activities (building, simulation, and design) is intended to help students make connections between the mathematics and theory, and the actual physical mechanisms. The students predicted results based on their calculations then built designs and observed the outcome. The students worked in pairs on the design projects and produced a variety of designs. One student pair is shown in figure 7. Student comments regarding the design projects are given below.