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Re: [Phys-l] Any teaching tips

Hi all-
I think that the suggestion that equations be abolished is about half right; an equation should be acceptable if the student can derive it.
Feynman's "What I cannot create I do not understand" is, to my mind, an excellent teaching principle.
Regards,
Jack

"Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley




On Thu, 27 Jan 2011, Philip Keller wrote:

This is actually a very interesting and deep question. It relates to so much that we are called on to do as physics teachers.

I was recently telling my AP students, who I am now teaching for the second year (I taught most of them in Honors Physics last year) that I am tempted to banish the kinematics equations from my classes completely and require all solutions to be based on the graphs of position and velocity. Others here have also suggested this.

Advantages:

1. The no-equations method requires a deeper understanding of kinematics and the dance between physics and math.
2. There is no memorization.
3. The analytic skills required are then transferable to other settings.
4. Some of the most challenging back-of-the-book kinematics puzzles solve much more easily this way. This includes all of the variants on the commuter-chases-an-accelerating-train problem.

Disadvantages:

1. In my experience, fewer students have the ability to master this approach. The ones who do all find it easier but in what is already an honors level group, they represent maybe a third of the students.
2. For the typical problems that they are going to see on the AP, the SAT II and also on part of my tests, the traditional identify-three-givens,manipulate-the-equations method is in fact faster. And these end of year tests are a fact of their lives. In the short term, dealing with these tests IS a "real world" problem! And another real world problem that high school teachers face is that we do not really control our curriculum. I say that even though I have co-written my school's curriculum. But I can tell you that we were expected to prepare students for the SAT II and then the AP. In fact, the AP has to approve our curriculum if we want to call the class "AP Physics". I am tempted to recommend that we opt out -- let me teach "Advanced Expolrations in Physics". Set the robots free! But I know the culture of my school and I don't see this happening soon.

To return to the question that sparked this thread:

It is possilble that the ability to identify given information is a reading problem. You may want to coach your students to recognize certain code words:

"at rest" -- Vi = 0 m/s
"to a stop" -- Vf = 0
"at its peak" -- Vy = 0
"dropped" --- "Vy = 0 unless it was dropped from a moving object...

Also, I find that beginners often assume that a given velocity is the average vellocity. I tell them that it is usually not the case, and that when someone wants to tell you an average velociity, they usually provide it with phrases like "over the time interval..." or "between this time and that time".

Now, this all may qualify as robot training, but on the other hand developing close reading skills is certainly a worthwhile skill and one they will need throughout the course (and presumably elsewhere).


________________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu] on behalf of FOUAD AJAMI [fajami@bell.net]
Sent: Thursday, January 27, 2011 1:18 PM
To: phys-l@carnot.physics.buffalo.edu
Subject: Re: [Phys-l] Any teaching tips

The problem in kinematics is that there are many variables and many equations and students get confused.
I establish the following system to give them some structure.

For constant acceleration, tell students to place the 5 variables: vo(initial velocity), vf (final velocity) a (acceleration) s (distance) and t (time) in a table.
Let them read the problem and extract from the wording three numbers for any three of the variables, leaving two blanks (unknowns).
Search among the usual equations of kinematics - normally shown in any book - for the two most appropriate equations.
(Note that each equation contains 4 of those 5 variables)
This helps them get the numerical solution quickly.
For some combinations of unknowns, it will be necessary to solve the two equations simultaneously.
I always ask the students to then sketch the s/t and v/t graphs for the motion, so the method is not as automatic as it seems.

For constant velocity, the table reduces to 3 variables and one equation, so they have to extract 2 numbers from the problem.

For projectiles, they set up a constant "a" table for vertical motion and a constant "v" table for horizontal motion, and the "t" value is common to both.

The system works for probably all the problems in an algebra-based course
Fouad Ajami




Date: Wed, 26 Jan 2011 19:05:51 -0800
From: reginaldquinn2@yahoo.com
To: phys-l@carnot.physics.buffalo.edu
Subject: [Phys-l] Any teaching tips

I'm teaching Physics (Algebra Based), we are learning about kinematics in 1-D.
I have students that have trouble listing knowns and unknowns. I tried to get
the students to learn the units (e.g. speed is m/s, etc), so they would know how
to do this step, but it's been largely unsuccessful. Any tips?



_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l

_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l
_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l