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Posts Tagged ‘magnetism’

Teaching Electricity and Magnetism: Part II

March 30, 2011 2 comments

ResearchBlogging.org
This is the second part of my posts about teaching Electricity and Magnetism (EM). Part I can be found here, which dealt with the confusion of students in learning electricity and magnetism together. Part II deals with a paper looking at ways to help improve teaching methods for EM. The paper is entitled “Using multimedia learning modules in a hybrid-online course in electricity and magnetism“.

When I was still TAing (about 2 years ago) the University was starting to implement a new way of performing tutorial sessions. They were going to do it online. This was done by the students logging into a virtual classroom with the other students and were able to type out questions to the TA. The TA was in a computer lab somewhere and outfitted with an electronic on-screen writing tool (don’t ask me what it’s really called) and would work out problems on their screen by hand, which the students were able to see in the virtual classroom.

When asked if I wanted to participate in this type of tutorial, I refused. Call me a dinosaur (I’m only 26, but whatever) but I wanted to be in the room with the students when I taught them.

But do online and multimedia learning tools help? Or are they worse? That was the topic of this study.

A multimedia learning module (MLM) was developed by the Physics Education Research Group at the University of Illinois at Urbana Champaign and implemented as a pre-lecture assignment to students in an introductory physics course. MLMs are interactive online exercises which include flash animations which introduced physics concepts to the students. The MLMs were about 12-15 minutes long.

So the goal of the study was to determine if using MLMs prior to learning the concepts in class resulted in better grades for the students and a better student experience. The study tried them out in an introductory Electricity and Magnetism course in the Fall of 2008 at California State Polytechnic University at Pomona.

They used two different sections of the course as the control group and the experimental group. The control group (N = 48) had only the traditional coursework. The experimental group (N = 34) used traditional coursework in conjunction with the MLMs. To make sure any increase in performance was not simply due to increased time spent on the material in the experimental group (i.e. classtime + time spent on MLMs) the amount of time spent in the class was reduced by one-third for the experimental group.

Students in the experimental group viewed the MLMs prior to learning the material in class. Both groups were approximately equal in academic performance  prior to taking the course, as determined by a survey.

Student performance after the term was measured by a multiple choice test, as well as the results of answering questions in class using a personal response system called a  “clicker“. Students were also asked to fill out a questionnaire to rate the usefulness of different aspects of the course, such as the textbook or the MLM.

Students who used the MLM showed an 8% higher normalized gain than those in the control group (45% compared to 37%) in their multiple choice test. In addition, students who used the MLMs answered a slightly higher percentage of in-class clicker questions correctly (60 +/- 4.0%) compared to the control group (54 +/- 3.0%). This leads to an effect size of 0.25, which is considered a small effect.

Finally, students rated the usefulness of the different course material on a scale of 1 (not useful at all) to 5 (extremely useful). Students in the experimental group rated the MLMs higher (~2.5) than the course textbook (~1.3).

So does multimedia course material improve student performance? Well these results show that it is no worse than traditional coursework. One thing to note is that any increased improvement of the group which did MLMs compared to the control group is very small. With a sample size of about 40 students in each group, it is difficult to draw any firm conclusions.

In addition,

It is worth mentioning that the comparison of final exam scores between students in the control and those in hybrid-MLM group showed no significant differences.

So at the end of the day, students did roughly just as well in both groups.

But this is an interesting study nonetheless. Probably the best thing to do would be to offer the MLMs as an optional and additional resource to the students, without cutting out the in-class learning time. Everybody learns differently, whether it be through visual stimuli, auditory or simply repetitiveness. The important thing is to make resources available so people of all learning styles can benefit.

I felt I could teach my students best face-to-face, so I declined to use the new fangled technology for online tutorials. But I understand they are still being used, and some students actually prefer them. So I guess in the end, this study showed that no single manner of learning is better than any other. Do what works for you and stick with it.

Sadaghiani, H. (2011). Using multimedia learning modules in a hybrid-online course in electricity and magnetism Physical Review Special Topics – Physics Education Research, 7 (1) DOI: 10.1103/PhysRevSTPER.7.010102

Teaching Electricity and Magnetism: Part I

March 29, 2011 2 comments

ResearchBlogging.org

When I was a physics TA, there were two topics which always got the students easily mixed up. The first was Newton’s Laws; students had a hard time knowing which law to apply in what situation. But with a little practice and teaching, they soon found that you could follow a very specific procedure to solving any problem involving Newton’s Laws, which helped immensely.

Electricity and Magnetism (EM) was different, however. There really is no set procedure for solving an EM problem. There are strategies and guidelines, but no step-by-step ways of solving EM problems like there is for Newton’s Laws.

I’m not the only one who has noticed this either. Two papers were published this month in Physical Review Special Topics – Physics Education Research. The first was entitled “Interference between electric and magnetic concepts in introductory physics“.

This study looked at the difficulty students had in determining which direction the force on a charged particle would be, if it were in either an electric or a magnetic field.

For a positive charge in an electric field, the force is always in the same direction as the field. If the charge is negative, the force is in the opposite direction of the electric field. Students generally don’t have a problem with this rule; that is, until you introduce the concept of a magnetic field to them.

In a magnetic field, the force on a charged particle is always perpendicular to the magnetic field lines. So when you get to the end of the term and you ask an EM question, students often (understandably) get confused which rule they should use.

The main hypothesis of the study, therefore, was that students have trouble because they learn about electric fields first, and then apply those lessons to working with magnetic fields.

You can test this hypothesis by seeing if the opposite is true. Does learning about the magnetic field first negatively affect the way students answered questions about electric fields?

The subjects (I mean, ‘participants’ hehe) of the study were students in an introductory physics course at The Ohio State University. The students were asked to answer EM related physics questions. They were split up between groups which had learned i) nothing about EM, ii) electricity but not magnetism, iii) magnetism but not electricity, and iv) having learned both. The order in which the questions were asked and some other variables were randomized for better results. Below is an example of the type of question the students were asked.

Can you get the answer to this question? For the left hand side the answer is 'e - Into Page' and for the right hand side the answer is 'f - Out of Page'

There are actually several results from this study, so if you are interested in them all I encourage you to read it (it is free to read). But the main hypothesis turned out to be true:

directly after instruction about magnetism, many students answer that the direction of the force on a charged particle moving through an electric field is perpendicular to the electric field, presumably by employing the same right-hand rule that was learned for magnetic forces. Thus, despite the fact that directly before magnetic force instruction students were answering electric force questions correctly, up to two weeks (and possible longer) after they learn about magnetic force, they answer electric force questions as though they were magnetic force questions.

So the authors actually showed that it is not electric fields or magnetic fields alone that confuse students, but after learning both they get them mixed up, which makes sense. It doesn’t seem to matter, either, which they learn first. After learning both electric and magnetic fields they still get confused.

The authors suggest (and I agree) that to combat this the instructor must frequently point out the distinction between electric and magnetic forces. It is a difficult thing to get a feel for, kind of like learning the offside rule in hockey.

A good strategy is always visual demonstrations. Take for example this video of MIT professor Walter Lewin demonstrating the perpendicular magnetic force (jump to around 46:40 for the demonstration):

So what else could we do about students having trouble with EM? What about online and multimedia tools?

That will be the topic of Part II of this series.

Scaife, T., & Heckler, A. (2011). Interference between electric and magnetic concepts in introductory physics Physical Review Special Topics – Physics Education Research, 7 (1) DOI: 10.1103/PhysRevSTPER.7.010104