UCLA’s Computer Promoted Understanding of Physics Concepts (CPUPC) has continued to be a major tool for students looking to understand the basic principles of physics.
The software provides five separate experiments demonstrating the principles presented in the standard curriculum’s lectures and laboratories. Each experiment is further divided into a demonstration mode and a test/report mode. For example, one experiment illustrates mechanics principles using a bouncing ball. In the demonstration mode, students can vary the numerical parameters associated with the ball, such as initial velocity, vertical and horizontal components, or the presence or absence of air, and get a graphical representation of the impact of such variations. In the test mode, students are required to complete specific, assigned experiments and then are graded based on lab reports of their findings. “Here,” says Bercham, “they can’t play with all of the variables. We may change the value of the acceleration constant, for example, and then ask the student to calculate this unknown. Unlike in the demonstration mode, they can’t play with the widget that changes the constant.”
There is also a textual element to the simulations that contributes to the efficiency of conducting experiments, says Bercham. “If students forget a formula or principle, they can click on a field to open a window into the text from the relevant lecture. They can then go back to where they left off and just carry on the experiment.”
The software was developed using a network of workstations and servers from Sun Microsystems. The CPUPC application resides on a SPARCserver 670MP. Students can access it through 18 SPARCstation IPX and two SPARCstation 2 desktop workstations, networked via Ethernet and filesharing software. An additional SPARCstation IPX desktop workstation is used by professors for laboratory demonstrations in the lecture hall.
The developers chose to rely on workstations for the project because they felt that neither the Macintosh nor PC platform would be powerful enough to handle the real-time graphics required by the application. For example, says Bercham, in simulating a water tank, “we needed enough speed and power to show the water and what happens when you do something to it, such as launch a wave.” While other platforms may be able to handle this type of simulation, many would be incapable of providing real-time interaction. “It’s like making a movie, but you need to be able, at any time during the movie, to change something and see the result right away.” The challenge, he says, is a function of the fact that the images are not pre-calculated objects. “When you’re doing a simulation, you’re calculating on-the-fly. So, in fact, when we’re displaying, we’re still calculating at the same time.”
Examples of some of the other experiments include a simulation of sound, showing how a sound wave can reflect and refract and the impact of certain effects, such as the Doppler effect. Another depicts an oscillator and the impact of such variables as mass and friction. All of the experiments involve “real simulations,” says Bercham. “It’s not just a formula that we put into the computer. It’s a step-by-step reintegration of the equations.”
The benefits of such technology in the classroom range from the obvious to the not-so-obvious. In the former category, explains Bercham, “You can repeat an experiment as many times as you want; you can change the parameters, so you can kind of explore things at your own pace to understand what’s going on. Students feel freer to test their intuition because it’s not just a one-shot thing.”
Often, in a traditional lab setting, students are more concentrated on just getting through the requisite components of an experiment before the class ends. “I remember when I was a student,” says Bercham, “sometimes you were just following the instructor and trying to do things as quickly as possible because you knew you could only use the apparatus for a limited amount of time. So you were trying to carry out the experiment without really understanding it. With the computer, you can say, ‘OK, I don’t understand, let’s go back and do some reading and then come back and try again.'”
Additionally, students are often inhibited by laboratory apparatus, fearing that they may break something. “With a simulation, if something breaks, we don’t care. We just have to restart the program,” says Bercham. Access to the technology also provides students with computer experience they will likely need in a professional setting when they finish school.
A more unexpected benefit also emerged once the system had been implemented. “We were surprised at first, because a large percentage of the favorable responses [to the system] came from the female students,” says Bercham. It seems that many of the female students had less experience than their male counterparts with the hands-on type of activities that are required in a physics lab–“just things like taking a screwdriver to put a mass to a spring of an oscillator, or tying things together,” says Bercham. “With the computer, everyone’s equal. Once you know how to play with the mouse, you can take off.”