# Day 118: COE WB’ing and Sledding

Today we WB’ed four of the six problems I had assigned last night.  I choose one problem (a pogo stick problem because I have a pogo stick a class several years back all chipped in to get me) and I let them choose 3 of the remaining 5 to complete. I like these days because it gives us a chance to practice some conceptual questions.  For example, one of the problems was a spring launching a mass vertically, I know you all know the problem.  I asked about what effect doubling the spring constant would have on the maximum height… or the ‘take off’ velocity.  I also asked them to predict the shape of a graph of height as a function of compression of the spring.  If I had thought about it earlier, I would have had a Logger Pro graph waiting on the wings.. or better yet a Vpython (or Glowscript) or even Excel spreadsheet with slider bars.  Well, there is always next year!

General Physics:

Today we went sledding.  We used the LabQuest2 (well the x-accelerometer) to measure the acceleration as the students rode down the hill. There are a few things I had not thought about ahead of time.  First of all was the fact that some kids did some spinning, also that it would be measuring the acceleration once the kids were on the horizontal part.  Hopefully the were able to get some meaningful data.  I did not really have a chance to look, I was serving up the Hot Chocolate!

# Day 48: Introducing 2D motion and Plotting an EOL with LP

After returning and discussing the test from yesterday, I had just enough time to introduce the next (unit) experiment. We will be starting in on 2D motion with projectiles.  I know there is some debate about when to ‘cover’ this.  I like it right after the two uniform motion units because it is simply a marriage of the two.  I like how the graphs of position and time and velocity and time for uniform acceleration are still fresh in the minds of my students.  When we get to forces, this is a nice chance to re-visit WHY there is constant velocity in the horizontal direction.

To develop the relationships, we simply do some video analysis of a projectile.  The students will produce four different graphs: horizontal position and time, vertical position and time, horizontal velocity and time, and vertical velocity and time.

General Physics:

We finished the motion detector activity and then learned how to have Logger Pro plot and EOL.  This is the same process we used with the advanced students.  Our goal is to help the students see Logger Pro as a problem solving tool, rather than just a graphing program.  The activity had them plot the position-time graphs for two cyclists.  For one of them, only the initial position and the velocity were given.  The student generated time values within Logger Pro, then created a calculated column for the position.    They also learned about how to use the Examine and Interpolate features.  I’ve said it before and I’ll say it again… I love the Logger Pro.

# Day 38: Holy **** Vernier Data Sharing Rocks

As I explained yesterday, we are working our way through an activity with the phan cart.  The two main objectives are to master making the (kinematic) stack-o-graphs for accelerated motion and to learn to solve constant acceleration problems graphically.   Yesterday when I asked the class to graphically determine the acceleration  from one of the phan cart trials, one (maybe two) group(s) of students realized data was needed from the velocity-time graph. They asked me to provide two points so they could calculate the slope.

The next problem I was planning to ask them to solve was to use the velocity-time graph to determine the change in position during the time interval the cart was out of my hand. (I let it go and then caught it a bit later.)

Last night, after I wrote my post,  I decided to play a bit with a LabQuest 2 and motion detector I brought home.   I knew the LQ2 could share data and set up it’s own wifi, but I had never bothered to really try it in class.  As I was reading some help files from the Vernier site, I learned that the new version of Logger Pro (I’m running 3.8.6.2) has a Data Share feature (found under the File menu).  So I decided to give it a try in my classes.

All that I needed to do was to have each group login and open a browser window. I displayed the URL established under the Data Share option on my Smart board, the students enter it and voila… my data shows up on their screen!  (It could also show up on an iPad, or iPhone…)

At first I was a bit bummed that the graphs were not displayed in Logger Pro, even though that was what I was running, the Data Share analysis tools are not as good as the Logger Pro analysis tools.  BUT, then it occurred to me that this was actually a blessing for this activity, because the students actually had to decide what information was needed and grab the important times and velocities from the v-t graph (I told them they could check it using the x-t graph but they still had to show the work from the v-t) …not just use the Integral feature.

Here is what it looks like on the student screen:

and now a close up:

It was so easy to set up and the students really liked having the graphs right in front of them.  I loved that they had to determine what data to gather rather than one group asking for the data and then the others just using it.

I definitely need to play with all these features more.

So yeah, the Data Sharing ROCKS, thanks Vernier! And yeah,   I WANT MORE LABQUEST 2’S.

General Physics:

We WB’ed the mirror experiment and the students now see that the Thin Lens equation is actually he Thin Lens/Mirror Equation.  It was pretty cool to see that they could make use of another experiment from their journal to complete this activity.  Tomorrow we WB a few curved mirror problem.

By the way… DID I TELL YOU THAT VERNIER DATA SHARE ROCKS?

# Day 37: The Phan Cart of Physics and Logger Pro saves the day

Yesterday the students took a formative assessment on kinematic graphs.  I used that to put together some teams that the students worked in as we checked the predictions for the 7 different situations involving the motion of a phan cart (OK… a dynamics cart with a fan assembly). Here are this handout with the situations.Physics Phan Cart Phun.

SIDEBAR:

The fan assembly I use is from Pasco and I have the pulse assembly. This allows  the length of time the fan is on or a delay before it starts to be used.

There are two main objectives for this activity.  The obvious one is to gain more practice thinking about a situation involving accelerated motion and to accurately predict the kinematic graphs.  The second one (and REALLY IMPORTANT) is to use it as an introduction to solving constant acceleration problems using a v-t graph.  This is a truly powerful problem solving approach that I want my students to master.  So, after we check the graphs, I ask an extra question or two… “Use the v-t graph to determine the acceleration”, ” Use the v-t graph to determine the change in position during this time interval”.

General Physics:

We are almost finished with our optics unit.  All we have to determine a mathematical method (equation) that can be used to predict image characteristics.  We saw the types of images formed by converging lenses is the same  converging mirrors, and likewise for diverging lenses and mirrors.

SIDEBAR:

The transition was great for this because one student asked “Does this mean the Thin Lens equation is really the Thin Lens/Mirror Equation?”.  Well, let’s find out.

The plan for today was to use the Thin Lens Applet to gather data for a converging or diverging mirror and test to see if the thin lens equation hold true for mirrors also.  BUT the computers I have would not run the Java so… Logger Pro to the rescue.  I quickly generated six different data sets (object distance and a calculated column for image distance).  Each student worked independently and tomorrow will team up to compare how they made it linear (by trying/making the same modification we did with the thin lens) and whiteboarding.

# Day 24: Graphical Solutions for cvpm Problems vs. Kinematic Solutions and The Lens Game

This was homecoming week, and homecoming week always culminates with a pep assembly.  This translates into only 42 minutes classes, except for those over our lunch mod — that mod stays the normal length.

So, what did I do in with only 42 minutes?  Well, I did not do much, but my students were pretty engaged.  I explained that they were going to work in small groups to solve 4 constant velocity problems.  Most of them I think thought “Four problems, 42 minutes, in a group , no problem”.  Most groups only finished 2 of them; not because they were super nasty, way too difficult, but because of two requirements I gave them.  Requirement number 1:  Every group member worked on every problem, so each student has his/her own solution, no divide and conquer.  If I am going to collect the assignment, it will be from one group member and I choose the one.  I use this technique often with group work because I think it fosters communication between the group members and it forces all the group members to be engaged. Requirement number 2:  The first two problems had to be solved using a graphical approach and a kinematic approach, and the last two can be solved either way, student choice. The graph could be a position graph or a velocity graph (though the position graph for these is much more appropriate) hopefully generated using Logger Pro.  After all, it is much more than just a graphing program.  This basic plan was developed with the help of my chemistry teaching colleague.

I really want my students to be able to solve problems both ways, it makes them better problem solvers.  Some of these kids (especially some in the more advanced math classes) tend to think they can just grab an equation and use it.  As you all know, some problems are MUCH EASIER to solve with a graph than they are with an equation or two.  The ultimate goal is to get the students to the point where they have a feeling of which approach to use.  Another added benefit is that if they get stuck going down one path, they can try solving it with the other method.  Likewise, if they are unsure of the answer, solve it the other way to verify it.

This idea of dual solutions is not really all that new.  The Minds on Physics-Motion book introduces it with constant velocity problems.  Others (Kelly O’Shea, Casey Rutherford and Mike Pustie) have given presentations and written about using a graphical approach to solve kinematic problems, usually constant acceleration.  I have also required it when we work those problems.  The new part for me was to use it with constant velocity problems. Now when we get to constant acceleration, maybe it will not be as much of an adjustment for the students.

General Physics:

The assigned individual practice last night was to finish the ray diagrams for the lenses.  To check the ray diagrams, we set up the optics benches. There are a number of reasons why we did checked it this way.

1.  Connecting the ‘pictorial representation’ to the physical set up and allowing the students to see the image.

2.  It reinforced the idea that we can see both real and virtual images without the use of a screen, just look back through the lens with your eye in the cone of light.

3. It introduced the optics bench and provided practice with it and locating images before we quantify it with the Thin lens experiment.

As we checked them, the students also completed a chart for their notes that summarized all the possible situations (6 total) for object locations and resulting images.  I see this as the linguistic representation.

In my long class, we finished the day off playing The Lens Game.  An awesome idea from a former colleague (Jeff Elmer) and member of our Share group.  I’ll snap some pictures on Monday when I warm the students up with it, but it is just some big (yet thin) wooden cut outs of lenses, images (real and virtual) and objects that have magnets on the back so they will attach to my whiteboard.  Then we play.  Given this object at this location,  with this lens, what image.  Or, given this object at this location and this image, what lens and where?

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

Homecoming week, just letting you know.

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 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.

# Day 9: More Logger Pro Love and A non-linear data set

With both levels (Advanced and General) I opened up an inertia balance graph I had created in Logger Pro.  I used to demonstrate a few of the other awesome features of Logger Pro.  The first was the Interpolation feature (under the Analyze menu).  Earlier in the week we did the Inertia Balance challenge where the students used their hand graphs to predict an unknown mass (a king-size candy bar).  The students immediately saw how much easier and more accurate this method was compared to the hand graph.  Another feature I showed them was a calculated column.  My original graph had 3 columns; mass added, total time, and period.  The period was the calculated column.  I showed the classes this as a preview to working with nonlinear graphs, setting the table for the process of linearization.  This lead us into a pre-lab discussion for an experiment that will give us a non-linear graph.

The Advanced classes are investigating the factors affecting the period of a pendulum. It was interesting to see the discussion among the class and lab groups about whether or not the amplitude affects the period.  I really did not do much other that suggest there is a really easy and quick way to see if it really matters… most groups decided to do a quick check with the equipment.  I did encourage the groups to stay away from really big amplitudes.

The General classes are investigating a mass on a spring.  They are just looking at period as a function of mass.  The spring itself as a factor that affects the period did come up in the pre-lab discussion.  We agreed to see if it is a factor by comparing the slope of the linear graph when we WB it.  I like this as the second experiment for the general classes because it essentially the same experiment as the inertia balance (period vs. mass), so there is no new procedure for the students to write, they are able to see that the data table is the same, gathering the data is essentially the same, BUT they will end up with a non-linear graph to work with.

# Day 8: Lovin’ the Logger Pro

In both classes (Advanced and General), we spent the first part of class completing two independent peer reviews of student lab journals.  Each student read through two other journals, completing a feed back rubric as he/she went.  I have found that this helps the overall quality of the journals, especially for the students that have never kept a lab journal.

The rest of class was spent feeling the ‘Logger Pro love’.  The classes worked through a Logger Pro tutorial on basic graphing that I made by modifying one that comes Logger Pro.  It has the students follow a set of steps to set up the columns, enter data, put o the linear fit…  the data plotted was what each student gathered in the Inertia Balance experiment.  It was a nice opportunity to talk about our ability to draw the best fit line… comparing our calculated slope with what Logger Pro gives us.  The Logger Pro love comes from me telling my classes “I love the Logger Pro’.  One year a class even made a class T-shirt with I (heart) Logger Pro on the front.