Re: Teaching Magnetism

[John Clement <clement@HAL-PC.ORG>]

Excellent, at what level is this done?  My students have already heard
of N and S poles, but they then wish to call them + and - and make the
magnetic model the same as the electric force model.  I would suspect
that this would be a good 9th grade activity.

The other problem that I see is that my bar magnets are very weak, but
with the disk magnets it is harder to see where the poles are located.
Also my bar magnets already have labels N on one end.

John M. Clement
Houston, TX

> Howdy-
>
> A few years ago, when I decided to get serious about teaching
magnetism, I
>  finally figured out a problem that many of my students had. They
thought
> that the "North" side of a magnet was the side of the magnet that was
on
> the north -- geographically -- side of the magnetic.
>
> Looking back at the text and the order of how I taught the material,
this
> interpretation wasn't all that unreasonable. I had spent more than a
bit
> of time discussing how iron could be magnetized by the earth's
magnetic
> field, and so on.
>
> Now, I teach magnetism differently. In the students' investigations
they
> discover that each magnet has two ends*. Picking one end, it is
attracted
> to one end of another magnet and repelled by the other. The other end
> behaves similarly but in reverse. The end that used to be repelled is
now
> attracted.
>
> I ask the students to come up with way to identify their magnet ends,
> offering sides "A" and "B" as options. Soon they notice that one
group's
> naming convention is not always the same as their own, and so they
often
> fight for a standard.
>
> When we do compasses they realize that the earth makes a handy
standard.
> -----
>
> One interesting side note. Most of students have already heard that
> opposites attract and they have dealt with static electricity, too, so
> they use a formulation like "A attracts B and repels A." Some students
try
> to come up with a system where the naming is like "Tab A goes into
Slot
> A." They never get far, but a few students try this every year.
>
> Marc "Zeke" Kossover
> The Hockaday School
>
> *I don't give students multi-pole magnets until very late. Do I look
like
> a jerk?