# Day 34: I screwed up… twice, and Whoa, that’s Freaky

Well maybe the title of this post grabbed your attention and that’s good.  You should read this and not make this mistake I did, especially since I know better!  By now you might be really curious….

Ok, enough drama building… the way I screwed up is by not listening to what I call “on the fly feedback’.

SIDEBAR:

On the fly feedback is something I hope every teacher does… gauge the class as he/she presents or discusses something.  I guess it could be considered a form of formative assessment.. helping teachers plan and alter a lesson as he/she presents it.

In my mod 1 class (Shorted again to ~48 mins because of the ACT Aspire testing for 9th graders),  the plan was to WB the instantaneous velocity vs.time graph and the (two) instantaneous velocity vs position graphs.  We presented the v-t graphs and that finally defined acceleration for us.  It took a bit longer because the kids were not really giving me any feedback (verbally) about whether or not they fully understood the v-t graph and acceleration.  I know (because of the look on their faces) that some students were confused as how there could be an object that gets faster and have a negative acceleration. (Recall I set it up that way on purpose so we could confront the issue of negative ‘a’ meaning slow down.)  Here lies screw up number one.  I took their lack of response to mean ‘they got it, go on’..   So I did, I went back to the x-t^2 graph to figure out the meaning of the slope.  Our data showed it to be 1/2a.  Again no real response so on I went.  On to the v^2-x graph where the slope is shown to be 2a.  I ended the hour with about a 3 minute introduction to “stack-o-graphs (x-t,v-t, and a-t).  I had an excellent plan based on the success of how I transitioned to velocity graphs from position graphs using video analysis.  I did video analysis of a free wheeling dune buggy going down a ramp and then created a calculated column for the acceleration so I could make an acceleration vs. time graph.  Then I made another one of the buggy going up the ramp.  I had these two files waiting… hardly started the first one with Mod 1.

Enter Mod 2:  I new I need to change a bit for this class.  Again I did not pay attention to my gut.  I thought, well, I’ll just do a better job of explaining the two other graphs, it’ll take less time.  This class is usually more vocal and this day was no different… many questions about negative acceleration and what the (-) means…  A quick glance at the clock… time flying by… not much time….Here is screw up #2.. I kept going?? But guess what…I did not even show any of the video analysis. My intro was way too rushed.  I should have stopped after WB’ing the velocity-time graph, then right to the two VA files.

Enter Mod 3… (At this point, I’m pretty pissed at myself, I know better that this, and I’m usually much better at the ‘on the fly feedback).  So what did I do with mod 3?  I did it the right way!!  I slowed down for the velocity-time graph discussion and did not even try to look at the other graphs/slopes.  It was a natural transition to the stack -o-graphs and my two really nice VA files.  We got through both with a bunch of discussion along the way.  I even thought to do a Quicktime screen recording that I posted for the other two classes as some help for the homework (7  Stack-o-graphs).  Monday WB’ing should be interesting during Mods 1 and 2.

General Physics:

They had three multiple mirror ray diagrams to make.  In my room, there are four long lab benches where the students sit, eight to a bench.  I gave one problem to each table and told them to agree on it, and make sure everyone understood it and could explain it and they had to have a nice picture of it. After about 15 min, I assigned each seat a number (1-8), the rolled my eight sided die twice. This two people had to explain the ray diagram they created using our document camera.  We followed each one by looking at the real set-up.  A set of infinity mirrors, a normal periscope, then a rotated periscope (the top rotated 180 degrees).  We also looked at a corner reflector and a two way mirror demo.  I’ll snap a picture of it tomorrow.  Basically its plexiglass with a spot light on each side.  Sit two kids across from each other, dim one side to superimpose the image (reflection) with the real person on the other side…. “Whoa, that’s freaky!”