Day 51: The Monkey and the Hunter; Walking v-t Graphs

Advanced Physics:

Today was about conceptualizing projectile motion.  We started with horizontal launches.  The first question was a ranking task. There were 9 situations with only two different heights.  The question was to rank the situations from the most time in the to the least.  There was a bit of extra info added: mass, and initial (horizontal) velocity.  We then moved on to the famous Monkey and the Hunter question.  We start again with the horizontal version.  Where to aim is the question. After some more discussion we test it with this set-up:

General Physics:

The main activity today was a kinesthetic experience with the velocity graphs and motion detectors.  It never ceases to amaze me that kids that have mastered the position graph can get tripped up by the velocity graph.  I guess it would have some thing to do with the ‘horizontal’ position is at rest, but horizontal velocity is constant velocity.


Day 50: projectile Whiteboardathon and Transitioning to v-t graphs

Advanced Physics:

Today was a heavy WB post lab discussion.  Each group prepared a WB for the horizontal component (both the x-t and the vx-t graphs) and another for the vertical component.  The post lab discussion usually goes like this:

Hertting: So when we look at all the horizontal position graphs, what is similar about all of the them?

Ss:  They are all linear.

Hertting:  OK, that’s a really good thing right?

Ss:  ???

Hertting:  Why would it be a good thing that the horizontal position graph is linear?  What does it tell us?

Ss:  The horizontal component is constant velocity.

Hertting: Ba Bam!!!

Then we discuss why even though the graphs are all linear, they seem to be a few varieties.  The students usually see right away that this is dependent on where they set the origin (in the VA) and which direction the object was tossed.

On the the vertical component:

Hertting:  So when we look at all the vertical position graphs, what is similar about all of the them?

Ss: They are all non-linear.

Hertting:  Good, so what does that tell us?

Ss: The vertical component is not constant velocity.

Hertting:  Good, is it constant acceleration?

Ss;  Yes

Hertting: How do you know?

Ss:  The vertical position graph is non-linear.

Hertting:  So ANY nonlinear position graph is constant acceleration?

Ss: ??? Well, no…

Hertting: So, how can you tell if it is constant acceleration?

Ss:  Look at the vertical velocity graph.

Hertting:  And ….

Ss: Well, this one is linear so it has a constant slope and the slope of a velocity graph is defined as the acceleration.

Hertting:  Nice… what value is it?

Ss: Is it it freeall?

Hertting:  Is that what our data shows?

Ss;  Well sort of?

Hertting:  What might cause it not to be free fall?

Ss:  We still stink at Logger Pro?

Hertting: (he he) Well, maybe just a bit.  What gets int he way of some of our projectiles?

Ss:  Air.

Hertting:  Good.


SIDE BAR:  I may have paraphrased that a bit… but not too much… lots of leading questions.  Take a look at this board:


It was of a bounce pass with a basketball from the right to the left.  it is the horizontal position graph.  I asked the class where the bounce shows up in the graph?  After a bit, they realized it doesn’t because it is constant velocity the whole time.  The actual LP graph was pretty linear as drawn.


General Physics:

We reviewed the video analysis process as a group and then we transitioned to velocity-time graphs using the video analysis as I did with the advanced students.  This is no doubt the best method I have used to transition to the v-t graph.  FV Nov 2013–VA to Transition x-t to v-t is what I shared with the Phox Share group.  It is really slick.

Day 49: (VA)^2

Advanced Physics:

Today was purely a work day for the students.  The goal?  Complete the video analysis of a projectile and prepare four graphs: x-t, y-t, vx-t, and vy-t.  Tomorrow we will have a glorious whiteboard session to determine the models that govern projectile motion.  It is kind of awesome when the kids are this engaged for an activity.

SIDEBAR:  This year they also uploaded the video they made to Schoology for everyone else to see.   I’m hoping for some really creative ones.


General Physics:

After a bit of review on position graphs — transitioning from the position graph to a written description followed by matching with a motion detector — the generals completed a tutorial on how to do video analysis with Logger Pro.  They used the video I made this time, the follow up- create their own constant velocity video.

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

Advanced Physics:

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 47: Test Theme and Walk

Advanced Physics:

Summative Test on constant acceleration… turned out to be a bit long.  Every test I write, I time myself and then give the students 3 or 3.5 times that amount of time.  Either I was a bit off, or they were slow.  The theme for my test also dawned on me as I wrote this test.  Each year for the last 6 or 7, I have written in a reoccurring theme test question.  For example, the year I had lunch duty, every test had a problem based on a lunch duty scenario.  Another year it was Prince Fielders inside the park homerun.  Last year, fictitious student FJ (who was really in my class).  This year, my principal.  We’ll see how long it is before he catches wind of it.


General Physics:

We WB’ed our first constant velocity problem set today. We also started in one the motion detector activity.

Day 46: Clicker Review and Ranking Tasks

Advanced Physics:

There were three groups that did not complete the Stunt Barbie test so we finished them.  I also created a short conceptual clicker review using some of the A2L (Assessing to Learn) clicker questions.  I like some of these because, if chosen carefully, they really foster some great discussion.


General Physics:

We reviewed the buggy lab main concepts and then completed 2 ranking tasks.  Ranking tasks are TIPERs. (Task Inspired by Physics Education Research) The two we used dealt with displacement and distance when given a series of position graphs, and velocity and speed given another set of position-time graphs.  We approached both of them using “Think,Pair, Share”.



Day 45: Testing Stunt Barbie

Advanced Physics:

Today was all about testing the Stunt Barbie Challenge Lab.  Most of the groups were successful, some on the second try. For each drop we record it with our highspeed camera and a regular camera.  We use the high speed to play it back if we need to check where the marble actually hit.

General Physics:

Today we WB’ed the Buggy experiment. We basically use the same discussion we do with the Advanced class minus the time-position graph aspect.

Day 44: Stunt Barbie

Advanced Physics:

We have pretty much wrapped up the constant acceleration unit.  Today we took a short assessment, a one problem constant acceleration problem the students could choose to solve graphically or kinematically.  I am happy to report that most of the students choose a graphical approach.

After the students turned it in the assessment, I showed them ‘some awesome physics.  It is this Farmer’s Insurance Commercial.


The most important part is when she jumps (free falls) off the bridge on tot he moving car beneath her…. and thus we have the Challenge Lab that I affectionately call “Stunt Barbie”.  Here is a good explanation: Hertting- Stunt Barbie

There have been some upgrades since the article.  We go into the multi-purpose room. It has higher ceilings so we have drops up to about 3.50m.  Tomorrow we check it.

General Physics:

The general students started kinematics today.  We direct this group just a bit more.  We introduced motion by discussing two key players, basically a ‘where’ and a ‘when’.  In physics terms this is position and clock reading.

They gathered data for the Dune Buggy experiment.  We still gave each group an initial position and a direction that will make the WB discussion a bit more interesting tomorrow.

Day 43: 30 minutes huh? That’s all I get today?

Classes today were only 30 minutes long today.  Students were dismissed at 12:10 because we had Parent-Teacher Conferences from 12:50 until 8:00PM and then again Friday morning from 7:45 to 11:45.  So, what did I do with 30 minutes?

Advanced Physics:

We had finished WB’ing the constant acceleration problems the day before, and the students had been working on some free fall problems.  Well, 30 minutes is not enough time to set-up and discuss WB’s for 4 free fall problems. Instead, the students essentially had work time.  The first order of business was to ask any questions about the free fall practice. Second on the list was to check their answers.  I created a ‘test’ in Schoology that was a Fill in the Blank format.  The students simply entered their values to all the problems, then hit submit.  If their answer turned green, they were correct.  If it turned red, they were incorrect. I gave them unlimited tries.  I liked this for two reasons: (1) it follows the color coding I have been using all year. (2) it allows the students to check their work, without being told how to do the problem.  It really fosters discussion and collaboration as they work to determine the correct answer.  I am becoming convinced that a student could trick him/herself into thinking s/he understands the concepts or problem as s/he reads through my work.

There is one drawback with Schoology and this.  It does not allow a range of answers, so I had to specific how many digits beyond the decimal point to use (some kids used -9.82m/s/s while I used -9.8m/s/s).

General Physics:

We finished discussing the test and then voted on our Magic Mirror pictures.