Tuesday, June 24, 2014

Modeling Workshop Day 4

Its only day 4; how can I already be so tired!

I am actually not that tired; actually right now I feel great!  But the participants and I are putting in a ton of mental (and a little bit of physical) energy.  Which I totally appreciate about the them.  They are awesome!

Today we did a bunch of stuff.  We started off, like we always do, with a discussion of two readings, some chapter 2 from Arons and an article by Jose Mestre.  

I feel like the participants didn't have as much to say about these as they have about the previous readings.  I wonder why that is?

They did, in my opinion, enumerate the salient points of the Mestre article which I affectionately call the "Holy Trinity of Instruction".  These are the three keys to good teaching; 
1 you must know your content 
2 you must know how students learn and 
3 you must know what student know when then get to you (misconceptions)

Each of these are crucial to good teaching.
Knowing your content is a minimum.  However, the extent to which you have to be a master is not clear.  For example, I have very little knowledge of advanced physics content but still do a fine job in the classroom.  Do I need to know about Hamiltonians and Lagrangians to effectively teach about mechanics?  I saw no.  I do need to know more than the kids so that I have a good sense of the nuance of the concepts but there is no need to be able to recite the standard theory of subatomic particles!

Kids learn by doing and to really learn (and complete a conceptual change) they must construct their own knowledge.  Studednts will learn very little from you telling them or them reading it.  They have to be engaged at all levels.

The idea that kids come in empty and its our job to fill them up with physics knowledge just isn't true.  Not only do they have a ton of physics knowledge most of it isn't very Newtonian!  We have to know what they are thinking and have strategies to help them change.  This doesn't mean our classes should turn into misconception which hunts, but we need to know what they think if we're to help them learn.

The Arons reading was especially important because it high lighted the fact that developing a concept should come before the vocabulary.  This was extended by the participants to include the idea that the concepts should also come before the equations.  I can't wait until we do the equation thing tomorrow!

After that we hit unit 3 pretty hard.  We finished looking at the position vs. time white boards they made yesterday by chasing the cart down the hill.  Then we did the same lab with the motion sensors.  Then we did the ups and downs and motion maps.  

Some of these ideas are very difficult, even for veteran physics teachers.  I saw some real (and I mean real) cognitive conflict for the participants.  How can the acceleration for a cart on a hill be negative the whole time when half of its motion is speeding up?

And should there be an acceleration arrow on the first dot - even if the cart was at rest?

As in interlude we did the T-Bone Challenge in the middle of the day so that we could pose for some pictures.  How did they do with the practicum?  only 1 out of the 4 groups got the cars to crash on the X.  What is up with that?  I love to see them really struggle and engage each other in authentic dialogue.  I hope they do better on the next one!

At the end of the day we did the velocity dance and ended with the balls on the ramps and tracks.

Today was long and took a ton of mental effort.  I hope that the participants remember how that feels when they're doing it with their kids next year!


Greg Huizenga said...

"What was up with that" referring to the only 1 in 4 collision was due to the curvy buggys!!!! Maybe those you have are past the 4-5 year warranty period ! :)

Bryan Battaglia said...

Sounds like sour grapes to me Pata!

Don Pata said...

The first time we do a practicum the participants are all like, "we are physics teachers, we should have no problem with this."

But then they miss and are all like, "It is the buggys; they don't go straight!"

No kidding! Its not like you didn't know that going into the activity.

But that's why I like it, they miss and it spurs on conversations about the activity, the buggy, procedures and other cool stuff that focuses on the process and not necessarily that answers.

Hugh Ross said...

Hi Don,

This is Hugh Ross, a workshop instructor from Indiana. We just finished Physics Day 5 yesterday of our two week workshop...and loving it. I'm enjoying reading your blog!

For our paradigm lab for constant accel, we focused on the instantaneous velocity vs. clock reading graph. We used a photogate at the top of the incline to turn on the clock, and a 2nd photogate at various positions to turn off the clock. This gave us the curvy position graph. The 2nd photogate also measured the eclipse time for a vertical rod on the cart, and this was used to determine the instantaneous velocity. What led to some wonderful discussion was that the y-intercept of the velocity graph was approx. 20 cm/s. I love that this lab gave an initial velocity because it provides a rich representation of constant acceleration. Thankfully, no one tried to linearize the instantaneous position vs. clock reading graph, which is a can of worms we didn't have time to deal with.

Anyways, thanks for your blog. I'm looking forward to how your energy day went...We'll tackle that model on Monday.


Don Pata said...

Hugh - thanks so much for the comment. I really love to hear about different methods for the same ideas.

Here is my initial question; by setting the distances and measuring the elapsed time (I suppose it is a clock reading that starts at zero with the first photogate) do you have any problems with the participants asking about which is the dependent and which is the independent variable?

If you set the distances and then measure the time, shouldn't you plot the distances on the horizontal axis?

I do, however, love to use the photogates to find the speeds at different positions or different times. My problem with photogates (and this is mostly with students) is that they seem like magic. Where does this velocity come from?

I guess you could say the same about the sonic rangers, however.

I love physics!

Keep up the good work.


Are you on twitter?

I am at @mr_pata

Hugh Ross said...

I'm following you now on twitter....one of my workshop participants, Andy Neutzel, recommended that I follow you. I'm new to Twitter: @ForceBeWithHugh

We began observing the motion on the incline plane and made motion map, X vs. t, and V vs. t predictions, so my students and workshop participants have no trouble dropping the IV:x-axis convention. No one really wanted to interpret a clock reading vs. Instantaneous Position graph anyways.

In the pre-lab, we ran a dunebuggy with a vertical pen attached to it through two gates to demystify the technology. Lo and behold, the average velocity between the gates was the same as the instantaneous velocity at the second gate!. I'd be glad to share the Logger Pro Photogate set up file with you (it took me a while to set it up since I didn't want it to calculate velocity for the students...too black box for me).

Of course, when we do the picket-fence free-fall deployment of the CA model, students can understand how the technology works at that point (and it's like an entire lab worth of data gathered in 1 second).

But the bottom line is, I think we should be focusing on the instantaneous velocity graph as the key representation of constant acceleration model, and I believe that should be the focus of the paradigm lab as well as the deployment. Curvy positions are simply an indicator of Acceleration, but finding instantaneous slopes and constructing the v vs. t graph from those was way too teacher-driven for me, and the model gets lost.

...and don't get me started on the slew of kinematic equations that many modelers still cling to. With the right velocity graph, we should be able to solve any kinematics problem. 1/2 a t^2 shuts down all thinking from what I've seen in years past with my students.

Thanks again for your insightful blog!

Don Pata said...

I am totally with you on the velocity vs. time graph as the key to understanding the constant acceleration particle model. In fact, I totally used to do it that way (for years) with the photogates.

They got that linear graph, and then used the area to find the position vs. time graph. I loved it but my students never seemed to make the connections that I wanted :(

That is why I went away from it. Maybe I should go back next year in the workshop and see how it goes?

I love that you feel too many physics teachers are still clinging to the slew of kinematic equations. Modelers are a little bit better - but new modelers especially can't seem to get over it.

In the end, this is what I love about the various modeling workshops around the country. They are all of the same flavor but the specifics are often quite different.

Keep it up!

Hugh Ross said...

I've been thinking about how you love the variety of modeling approaches used around the country. My favorite part of instructing a workshop is my interactions with my co-instructors. I always learn so much from their different approaches, and it inevitably gets me fired up about trying approaches that I hope will improve the quality of the students the students' models.

I was also thinking about the 4 co-instructors I've worked with over the years. Here in Indiana, most of us are on the same side of the "modeling family tree" going through Gregg Swackhamer to Malcolm/Dave H. I'd love to co-instruct with modelers who trace their "modeling pedigree" back through Larry Dukerich or through other routes. I other words, some more cross-pollination of ideas between leaders at the workshop leadership level would lead to more unity (and perhaps healthy diversity) in the modeling community, and perhaps a synergy that brings modeling to a new level.

Don Pata said...

I am totally with you.

My first experiences were with a Michigan Modeler named Mark Davids - who is now retired. He was instructed in 1997 and 1998 in Akron Ohio in one of the first workshops ever held.

He taught it in Michigan in 2000 which until 5 years ago, was the only time it was held in Michigan.

Almost everything I do I learned from Mark.

After that I spent 3 summers at ASU in workshops taught by Larry Dukerich and Rich McNamara and Kathy Malone.

I actually liken the Modeling Method to martial arts. There are different schools of let's say karate but there is one master and each of his master students often opens their own schools; with their own personal interpretation on the art form.

I feel like that is what we are doing. There is a push by the AMTA (a group with which I only have a loose affiliation) to standardize the workshops. I am not opposed to that in any way - but I am a little scared by their "my way or the highway" approach.

In the end I think that more cross pollination would be healthy for all of us who teach workshops. But who has the time?