Tuesday, November 17, 2009

Simulations are Not Science

Simulations, especially animated simulations, are a great learning tool. They can help students visualize and understand difficult concepts in science classes. Interactive animated simulations can engage students with the concepts. However, you must be careful when inserting simulations into science labs, that is, into student scientific investigations.

Simulations in science have a long and highly-reputed history. They're really the output of calculations from a model. Newton used them to help him investigate his ideas about gravity. He even invented new mathematics to aid in his work. Until recently, the work involved in modeling (simulations) was intense and lengthy. Computers have changed all that. In fact, the first computer was used for simulations.

You might say that simulations are a hallowed tool of science, but they aren't science themselves any more than microscopes, telescopes, or spectrophotometers are science. Scientists don't investigate simulations; they investigate the universe and all of its contents. They may make models of their theories and spend considerable time adjusting these models to see how they may fit with real-world data.

Simulations in science education are another matter entirely. The issue of the appropriate roles of simulations in the science classroom has become very important lately due to the lowering costs of computers and the number of new science simulation options being offered to educators. How should one take best advantage of this sudden abundance?

An example may aid in this discussion. Consider projectile motion, one of the earliest and most common science simulations. For the simplest case of a projectile in a vacuum and a uniform gravitational field, there's no problem writing the equations of motion or calculating the projectile path and impact point. The projectile position is a simple function of time and starting parameters such as initial height, angle of launch, launch energy, and projectile mass.

Indeed, the equations are so simple that a student can perform the calculations necessary to determine the projectile path for a given set of parameters in minutes with a hand-held calculator. A beginning student of computer programming can write a program to print tables of the position in a very short time. All that an existing computer simulation does is save time and, if animated, display the projectile motion.

All of these approaches begin with an assumed equation of motion. Should students be working to discover this equation or using it in some other fashion? Are they investigating a mathematical formula or learning about gravity and motion?

An instructor might have students investigate the motion of real projectiles with the goal of elucidating ideas about motion. Then, these ideas could be used to create a mathematical model. The model can be used to generate data to compare with the real data. Error analysis will help to determine whether discrepancies are within the precision of the real experiments or whether the model has flaws that require revision of the original ideas upon which they were based.

This approach uses simulations in an entirely suitable fashion, one parallel with that which scientists use.

On the other hand, an instructor might decide to use an animated simulation of projectile as the object of student investigation. An entire set of questions could be posed for resolution by the process of trying different parameters in the simulated model. The intended object may be science, but the actual investigation is of some equations, and error analysis, etc. do not enter into this activity at all.

Unless this instructor issues a very strong caveat, students may develop a misunderstanding of science when performing this exercise. The equations have unlimited precision, unlike the real world. They also represent an idealization of the real world.

The gravity field is not uniform. The projectiles do not move through a vacuum. Imprecisions exist in the measurements of the parameters. Investigations of the real world will illuminate these issues and help students to understand science. Science courses are not simply about memorizing content. While simulations may help with content, they have to be used very, very carefully in the investigation part of the course or not at all so that they don't interfere with the important learning that should go on here.

Educators should stop using simulations as the objects of investigations and very carefully use them to augment investigations appropriately or not at all.

These statements should not be interpreted as a license for hands-on purists to decry the use of virtual labs in science courses. Hands-on experiments have their own problems and will be the subject of a later blog entry.

Smart Science® education has found one way to thread the path between the science learning benefits of hands-on experiments and the efficiency benefits of virtual labs.
© 2009 by Paracomp, Inc., U.S.A. www.smartscience.net
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