Monday, June 30, 2014

Fsubscript more like WTFsubscript

This was mentioned in a blog post and I can't stop thinking about it!

In a blog post one of the participants queried as to why I didn't use standard notations like Fg, Fn, etc.  I almost fell off my chair!

I can't believe that after working so closely with me for two weeks anyone would not see that I'm all about the most basic conceptual understanding for the students.

The only reason I listed the nicknames of the forces was to:
1. Show anyone who doesn't have fully developed content knowledge where the text book names come from and
2.  Help the still traditional teachers in the workshop feel better about the names of the forces.

Apparently this backfired because there is still an idea that Fn and Fg are appropriate in any way.  To be clear:

The first rule of forces says that all forces must be exerted by physical objects that are made out of matter.  That is why we never say, "gravity pulls objects down" because "gravity" is not a physical object, it can't exert a force, it is not even a thing!  Can I hit you with a gravity?  Can you buy a gravity on the way home at the gravity store?  NO!  Then why would I ever roll up with Fg - the force from gravity?  I can barely even type it, my hand are shaking!

To list the forces as Fsubscript horribly confuses the students.  Writing the names of the agents next to the forces is the least abstract.  Writing forces and Fagent object is a little more abstract but still acceptable.  But Fg and Fn - come on!  You can do better.

I have seen too many traditional student struggle with naming.  Two common issues arise.  The first is with Fg.  So many traditional teacher tell the kids the Fg =  mg.  Do you see why this might be a problem?  If the notation isn't crystal clear to kid (without context) they just think that F = m (because the gs cancel).  Or even worse, the force of gravity = milligrams!

The other arises from Fn.  For years I heard traditional students ask about the "natural force".  I was like, "what in the hell is the natural force?"  It turns out that the teacher was saying "normal force" but without any context to know what "normal" meant they were reverting to this idea that Fn meant natural.  I assert that this is because in their math classes ln means natural log (something else they don't understand) and they thought the notation was the same.  Who could blame them?

So maybe it was my fault for having introduced the nicknames before we all got to know each other well enough.  Maybe I should have stayed with the names that made the most sense (perpendicular surface force, force of the entire Earth, etc).  If so, I'll do better in the future.

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