Day 20: Yet Even More Logger Pro Love and Snell’s Law

Homecoming week, just letting you know.

Advanced Physics:

We started off with a short assessment.  The students were given a written description of a motion (with positive and negative velocities and some rest) and asked to create the matching Motion Map and Position-time graph. Most of the students did very well.  There were a few that did not do so very well. Mostly n the motion map.

SIDEBAR:  Are you teaching Motion Maps?  I wrestle with it every year.

When the student turned in the assessment, I had them write their color on it next to each objective as I described in an earlier post.  I also add my color, I think this is a great visual for the students.

After the assessment, we looked again at Logger Pro.  So far we had used it to graph (to analyze data)  to solve a problem (by plotting an EOL), and as a way to gather data (with the motion detector).  Today was the day we married the data gathering with the analysis. In other words, we learned about video analysis.  They worked through another modified tutorial I created with a movie I made.  The follow-up assignment will take this to the next level;  they will create a constant velocity video and then analyze it.  This one will be uploaded to Schoology for the rest of us to see.


General Physics:

Today was some group practice solving problems with Snell’s Law, we WB’ed a set of homework problems.  This was the first problem set we worked on then WB’ed.  There were way too many kids that did not do it.  They found it a challenge when WB’ing.  To make sure these kids were still somewhat help responsible for participating and working in the group, when we started the WB’ing, I said that if you wrote on the board, you were not allowed to do any explaining, thus it fell to the other group members.  A bit sneaky, but hopefully motivating nonetheless.



Day 19: Wait, what? I only get them for 30 minutes today?

That’s right, you read that correctly.  We had 30 minute classes today.  It was out first PLD of the year.  The students were dismissed at 12:10.  The science department met from 1:00 to 2:40.  The topic you ask?  Common assessments. There has been a push over the last year or two to build common assessments for courses that have multiple instructors all teaching a section or two.  In our part of the department (chemistry and physics), we have been doing this for  a really long time already.  The new work this year is to tie a DOK (Depth of Knowledge) value to each and every question.  Here are the vales we can assign:

Screen Shot 2014-09-28 at 6.07.51 PM

We had an interesting discussion about this (as you can imagine).  It seems to me that we are to move away from the lower end questions, and multiple choice questions that are at that level.  Thankfully, I teach physics… no problem getting to the DOK’s of 3 and 4.  Our AP Bio II instructor pointed out that the AP tests are still using MC questions, but at a very high level… thank you very much.  The last piece we need to add is to tie each question on the assessment to one of our course objectives (or standard, or benchmark, or learning target or… we really need a common definition of all of these).   It amazes me to think there are tests being given with that have questions that do not tie to an objective and even courses where the kids are given the objectives!

After this meeting we had some breakout technology sessions.  For what’s it’s worth, I was really proud of the staff I work with, everyone was very productive for a beautiful Friday afternoon…. I know, inservice on a Friday afternoon!


So, what can you do with 30 minutes?

Advanced Physics:

My students finished the Walk this Way motion detector activity.  If there was any time remaining, they could use a compute to post their answer to a ‘Schoology” discussion question that I posted about a Hiker.  (More on this some other time).  They could also finish completing an assignment that had them using Logger Pro to plot two EOL’s (for two cyclists).  This skill is an awesome one to have as a problem solving tool AND it sets them up to be successful when I give them the Buggy Bash Challenge.

General Physics:

Yesterday we finished up the Snell’s Law experiment.  We showed them a few awesome demos that relate to the index of refraction.  Here they are:



We always try to do a sample problem with the new models before we sent the students off to do some individual practice.  The sample problem always involves real equipment and we work through it as a class.  Today we used our Refraction tank to solve for the index of refraction of a mystery liquid so it could be identified.

Screen Shot 2014-09-28 at 6.24.48 PM


We use PIPES as a problem solving approach.

P= Problem (what are you solving for)

I= Information (list everything you know, your givens)

P/E:= Plan and explain HOW you will solve the problem . (I like this step because it allows me to teach/preach about working backwards as a way to tackle longer and more challenging problems.

S= Solve it according to your plan.

Days 17 and 18: About last night… or Two for the Price of One

So I did not get the post written for last night, but I have a great reason. Notice I did not say excuse.  Last night was our first Share session of the year.  We have a local share group we call the Phox Valley Physics and Physical Science Share Group.  The Phox might need some explanation.  The ‘ph’ pronounced with the ‘f’ sound is because of the physics and physical science connection and the so the name sounds like Fox, we are located in what is known as the Fox Valley region of Wisconsin.  You can follow us on Twitter @PhoxShare.

This is an ABSOLUTELY INCREDIBLE group of devoted educators.  Many of the members are on Twitter and you should follow them… (@BrillionNerd, @MrTSchwall, @jcon16 to name a few, there are more…) For the last 14 years we have been meeting five times each year (September, November, January, March and May). Without question, this is the best professional development I get each year. I mean, what could be better than sitting down with a bunch of other physics and physical science teachers for a couple of hours to share ideas and pedagogy.  I am a very lucky teacher to be part of this amazing group.

I could go on and on and on and on…  but I won’t.  My suggestion, find a group near you or start your own.

Day 16

Advanced Physics

This was the first problem WB session of the year.  It was a worksheet that just started putting some of the cvpm representations together; position graphs, motion maps…  So not much to report.  I do tell my students that the focus and responsibility falls on them to ask the questions during the presentation of the solution.  I tell them if I see an error, I may or may not say anything about it.  The balk a bit, but I explain that if I was just going to confirm each and every board, there is not much point is explaining them… I feel guilty about this… but just for a minute or two.  You see, I check to see how much each student completed the night before.  I have a small conversation with each group as the prep the board.  It gives me time to talk one to one with most students.  Sure it takes some time, but I find many will ask a question there rather than to the whole group, especially at first.  It also lets me remind them to ask for help.  Early on, this might be a typical exchange:

S:  I did not get it done.

Me:  Ok, was it a I did not have time” or I did not understand?  I can’t help you  with the no time but I can help with the I don’t get. Send me an email or even a message via Schoology…

Usually gets the point across.


General Physics:

We gathered data for the traditional Snell’s law experiment.  Here is our set-up:

Snells law

Day 17:

Advanced Physics:

We started the hour off with a bit of practice.  I provided a motion map and asked the students to provide a written description of the motion (linguistic representation) and a position graph.  I used the “Think, Pair, Share” approach.  It was awesome to see the level of dialogue, none from me.  We also started a Motion Detector activity.  I’m sure most of you do something like it.  A set of directions about how to walk in front of the motion detector, then sketch the graph…  Working to build that kinesthetic experience.  Amazing some kids can explain it all, yet, struggle to walk it.

General Physics:

Today was the post-lab discussion for the Snell’s Law experiment.  This is a tough one because the linear graph is not one of the usual ones we get.  It takes some discussion to get the kids to see we should try plotting Sine Angle of Refraction vs. Sine Angle of Incidence.  In the second class, I actually followed he note I left myself last year…. plot incidence on the Y-axis so the slope is the index of refraction… MUCH easier for the general kids.


Day 16: The cvpm is finalized and Modeling the Pinhole Camera

Advanced Physics:

Today was the teacher talk part of the dune buggy lab.  Teacher talk may not be the right (or pretty) phrase… but it is, unfortunately, a a good descriptor.  I did too much talking , well actually I asked a whole bunch of questions as we summarized the dune buggy lab.  When discussing the position-time graph, I find some of the advanced kids just want to jump right to the ‘speed is the slope’, and when I say, well, not quite… these student switch to velocity.  I try my best to build the concept first…the slope of this graph is:

1.  the change in position  (later defined as displacement) in a time interval of 1.0s.  We develop this right from the units on the slope,

2. the rate of displacement

OK, lets give this concept it’s own name —> Velocity.  I wholeheartedly buy into the concept first, name second idea (thank you again Arons)

In the end, we wrote the general mathematical representation:  xf=(v)delta t + xi


We also built a new way to picture motion, the motion map.  We built it from a strobe photo of a dune muggy in motion.  Well, to be honest, it was  a series of pictures of a dune buggy on my Smart board.  It would be really awesome if there was an app that would do this for me… I wonder….


General Physics:

Today was about building the ray model from the pinhole camera activity.  We started by agreeing on the observations we made with the pinhole camera.  We then developed the need for a ‘line of light particles’ because we could not draw enough of them and they were so close together, it looked like a line– this became our ray.  I used  bamboo skewers to represent the rays coming off the light bulb and an index card with a hole punched in it as the pinhole.  We were able to physically model everything we observed during the activity.

SIDEBAR: Should have snapped a picture of this….

We also discussed that the light travels really fast — at light speed! yes, that really was a student answer… well, I did ask the question.

From here we talked about what we what we could do to alter the path of the light.  A mirror was suggested… true, but not what I was looking for. I was looking for change the medium.  Upon reflection, I think I should have tried asking  “What could be do to slow down or speed up the light”.  I think this would have been better… more natural to say “change what it travels in”.

Anyway, we built the concept of refraction using the old water tank demonstration.  I defined refraction as the change in the path of light as it travels from one medium into another.  The shift in the path caused by  a change in the speed of light.    Yep, next time, I will ask about changing the speed.

This demo also allowed me to define the normal, the angle of incidence, and the angle of refraction, setting us up for a Snells’s Law experiment tomorrow.

Day 15: WB the Buggy Lab and Why we start the General class with Optics

Advanced Physics:

It was a different style of WB’ing for the students.  Today each group presented its ‘ buggy experiment. I like to have each group present and explain the procedure followed because I find it can help set the tone for the class… we use discussion ALOT, and one has to be perfectly clear when explaining things.  As I explained in the previous post, I guide each group in terms of an initial position and direction.  To help with connecting a group’s procedure to everyone else’s, and to the graph, I make a suggestion about how to organize some of it:

Screen Shot 2014-09-22 at 9.31.15 PM

As expected, there was a mixture of graphs… some position as a function of time (clock reading), and some time as a function of position.  In all the classes, the students were able to identify the meaning of the vertical intercept for all the graphs AND for some of the graphs, the meaning of the horizontal intercept.  Most classes also hinted at the sign on the slope indicating direction of travel.  Tomorrow will build the conceptual meaning of each slope THEN give it a name… thank you very much Arons!


General Physics:

As explained previously, we start the General classes with Geometric Optics.  This was an idea I picked up from Jeff Elmer (formerly of Oshkosh North).  The advantages are just too numerous to ignore.  Here they are as I see them:

1.  Super high interest—> a bunch of really cool things to see, literally.

2.  It can be taught in a very conceptual manner.  Using ray diagrams, linguistic representations and essentially two ‘equations’  (the thin lens equation and what we call the similar triangles equation relating the heights and image and object distances) all of lenses and mirrors can be handled.  This puts the math-phobic students at ease as we start.  It gets them used to being a physics student without worrying about all the equations they may have heard about.

3.  The General kids get ‘behind’ the Advanced kids.  We start the Advanced class with Kinematics.  They are done with the constant velocity and constant acceleration models by the time the general gets there.  This means that when the ‘generals’ ask their ‘advanced’ friends for help with kinematics, most of the advanced kids understand it well enough to help in the way we want them to using our terminology…

So, what did we do today?  On the spur of the moment, we dusted off an old activity that we had gotten away from… the pinhole camera.  We will use it to build the ray model for light that we will use as the main ‘pictorial representation’ for our optics. It reinforces that we imagine the light to travel in a particular direction in a straight line. We can represent this with an arrow or ray.  It also naturally lends itself to drawing the ray diagrams to explain some of the observations we see with the pinhole camera.

Day 14: The Buggy Lab and The Mass on the Spring Challenge

Advanced Physics:

Like most physics teachers that model, I start the constant velocity unit with the (cv) dune buggy lab.  And, again like most, I have my own little changes that I have made to suit my own purposes.  Here they are:

1.  Through discussion, we develop the concept of position (not distance travelled) measured with a number line and clock reading, measured with a stop watch as the two variables.  I allow the advanced students to decide which variable to set as the independent variable.  This means when WB’ing, we get an interesting variety of graphs.

2. Once the students are out in hallway setting up, I talk individually with each group to answer any questions and to ‘guide them’ by assigning an initial position (not to be confused with the origin) and a direction of travel.  Half of the groups are assigned the negative direction and are told to imagine they have the negative side of the number line on the tape measure they are using; they just need to imagine little (-) signs on the tape measure.  They also need to add the (-) to their data.  To make it even more interesting, I have some start at a(+) position and head in the negative direction or vice versa.  These groups also usually pass through the origin.  Doing this also provides some nice variation when we WB, and, in the end shows a number of different possibilities.

SIDEBAR:  Assigning the direction and initial position, especially the negative ones, usually allows me to see which students are still stuck on distance travelled because they always get a positive slope and no intercept, when the should have a negative and some intercept.

3.  I alter the dune buggies when I put the cells in.  I have 3 or 4 of the older ones still working.  I can put cells in with the polarity reversed so the buggies run ‘backwards’ or ‘in reverse’.  If I am really on top of things, I’ll make sure a group that is supposed to go in the positive direction gets one so we can talk about using forward and backward to describe direction.  I also add aluminum slugs to some so they are really slow.

I’m looking forward to the WB’ing on Monday.


General Physics

These classes were able to see and talk about the graphing assessment they took. We also completed the Mass on a Spring version of the We Got The Beat Challenge.  Here are two student samples that were really pretty good:

Did you notice the Wilberforce Pendulum action on that one?

Monday, this group will start in on Geometric Optics.  More on that later.

Day 13: Re-assessment Policy Explained

Advanced Physics:

I returned the Graphing Assessment the students completed yesterday.  Today was the day to explain my re-assessment policy.  My students are allowed to re-assess on just about everything (NOT the final exam and not the conceptual questions on our unit tests.)  There are two conditions I have for re-assessment for full credit. Condition 1:  The student MUST complete some extra practice BEFORE re-assessing.  This is usually something posted on Schoology that we then talk about.  Condition 2:  To earn full credit, the student must have completed all the assigned practice before the assessment.  If the student did not complete all the practice, he/she can still re-assess, just not for full credit. (usually about 75% or 80%).  It amazes me how some kids do not take advantage of the re-assessment option.  My students get to keep ALL their assessments and tests. We go through them (usually) the next day and I tell them to make an ‘answer key’.

SIDEBAR:  Yes, I re-write a new unit test/assessment each year.  Not from scratch, but varied enough that I am not worried about the tests being around.

I explain to my students that they will not be getting a review packet when the final exam time rolls around.  We have been building our review packet the entire semester… all those ‘answer keys’.  I strongly encourage them to use the study technique known as self testing. (here is the research to support this)  They should cover up the solution to the problem/question with a blank sheet of paper and re-work the problem, then slide the paper down to check it.

After this discussion,  we finished checking the We Got The Beat Challenge… I still have Celine Dion stuck in my head…. grrrrr


General Physics:

Today the General kids took their Graphing assessment.  It’s all graded and tomorrow we’ll discuss the re-assessment policy with them.  We’ll also check their We Got the Beat Challenge.  Here is the video I made to demo the process for them:

They will put sand (or lead shot) into an overflow cup so they can get the exact mass predicted by their graphs/equations.

Day 12: Graphing Assessment and the Colors of Feedback.

In Advanced today, the students completed a Logger Pro Graphing assessment.  Because the Advanced students did experiment with a mass on a spring, the data set they were given was data for that experiment.  Every year I write a new assessment so I have other version to use an re-assessments.  I like this one because the class examined a linear graph that involved period (inertia balance) and a non-liner graph that involved period (pendulum).  Now they may not be sure … linear?? non-linear ??  Not only did I grade it for points, I also gave the students a ‘color’ on each of the objectives the graphing assessment was assessing. They are listed at the top of the assessment, and after providing written feedback, I highlight each objective with either Red, Yellow, or Green.   The colorful feedback system I use is pretty straight forward:

RED = STOP, the student has demonstrated NO mastery of understanding.  The student should come in or extra help.

YELLOW = CAUTION, the student has demonstrated SOME mastery/understanding.  The student needs more practice.

GREEN = GO, the student demonstrated complete mastery/understanding.

After the assessment, we had time to check two of the ‘We Got the Beat’ pendulums.  Here is the set-up I used to check it:

We Got The Beat

It was a laser gate with pendulum timing as the photo gate setting.


In General Physics, today we finished working on the graphing practice and introduced another We Got The Beat Challenge.  For theses students, they must create a mass/spring combination to keep the beat to a song.  Tomorrow they will take a graphing assessment.

Day 11: Wrapping up the Non-linear Labs with a Musical Challenge

Today in Advanced, we walked through a quick WB discussion of the pendulum experiment.  The students saw that the only factor the affected the period of the pendulum was the length. With eight groups, we had 4 different masses, with two groups doing the same mass. The students saw that regardless of the mass, the slope of the linear period squared vs. length graph was fairly constant.  We did not delve into what the constant(s) was at this point.  I explained, that as we did with our last experiment, we are going to complete a challenge.  The challenge this time was to create a pendulum that would keep time to a song playing in the background.  I learned about this awesome challenge from John Burke a few years back, here.  (although I think he credits Frank Noschese).  The students get no equipment, only the Logger Pro graphs and the EOL they developed.  As explained in Burke’s post, an on-line beat frequency website can be used to determine the beat frequency of the song the student group chooses.  I REALLY like this challenge . It allows some choice for the students, brings in some unit conversions and the relationship between period and frequency.  After the students predict the necessary length, each group (in turn) sets up the pendulum, we crank up the song and let it go.  We check the actual frequency using a Vernier Photogate with pendulum timing.  Here is a sample I made for the students.  Tomorrow after the Graphing assessment, we will check the challenge!

As explained yesterday, the General students worked on using Logger Pro to create linear graphs for three data sets we provided them.  They started the hour off with a quick WB of the Mass on a Spring experiment. They were able to see that the spring DOES have an effect.  Like with the Advanced group we did not worry about the exact meaning of the slope, just used it to show that the spring mattered, just like the inertia balance did.  I have to remind myself, that as long as I circulate around the room answering questions and pointing things out, the students work very hard.  Tomorrow they will be introduced to the same type of musical challenge…  determine how much mass will be needed to get their spring/mass system to keep the beat to a song in the background.

Day 10: Using Logger Pro to Linearize

As mentioned in the last post, our second experiment provided the students a chance to work with a non-linear data set.  Today, in both courses, the student finished gathering data and then worker through a second Logger Pro Tutorial.  This time it was on linearizing.  This is another one I modified from one of the tutorials that comes with Logger Pro.  I really appreciate the fact that those tutorials can be modified, tailor-made to my classes.

One of the interesting things I find students learn about working with linear graphs is the importance of a wide range of data.  For example, some of the Advanced kids working with the simple pendulum only varied the length from, say, 10 cm to say 40cm in 5 cm increments.  Their initial period as a function of length graph did look nearly linear.  With one group, we talked about a non-linear ‘thing’ looking linear because we were looking at such a small section of the non-linear part.  The ‘thing I referenced (in addition to sketching a nonlinear graph) was the earth and looking straight out.

The suggested practice(aka homework) for the Advanced classes  for tonight was to finish plotting for data sets.  The first two were pretty straight forward.  The third one was borrowed form a colleague from our Phox Valley Physics and Physical Science Share group (an absolutely incredible group of educators that might be a blog post at another time.  Follow us on Twitter  @PhoxShare).  Anyway, the premise for the problem is a series of video clips of a car traveling at a known speed between two markers, a known distance apart.  The data given is the speed in mi/hr and the number of frames it takes the car to go between the markers. In the past I Had the students actually download the movie and count the frames. The student use the 30 frames/second frame rate to determine the time in second.  I like this problem because it provides a chance to hint at using video to gather data, foreshadowing video analysis.   It also provides another chance to point out the importance of units on numbers… the slope of the linear graph is much easier to figure out if the speed is in units with seconds rather than hours. The four problem comes from the awesomeness that is Direct Measurement Videos and the work by Peter Bohacek and Matthew Vonk (and others).  If you have not looked at these yet, STOP READING THIS and go look.  I was fortunate to attend one of the DMV sessions this summer at the AAPT  meeting.  It was at this session where I learned about the Joly Photometer and using the DMV to develop the inverse square law.  I also ‘attended’ the Global Physics Department meeting two weeks ago when Peter and Matthew presented.  Besides being just plain cool, the Joly Photometer  problem will provide an introduction to the DMV’s that we will use at various times in the course.  I’m looking forward to seeing how the students performed on this one and their impressions of the DMV’s.

The General classes will work together in class on a similar set of problems tomorrow during class.  I found it interesting that my colleague (Mike Heidke) and I decided to do this in class rather than as homework this year AND this was a topic in a few of the Modeling digest posts over the last day or two.  It makes sense to do it in class… they can ask for help and it is more likely to get completed so the practice we want the students to have, they will get.