It works.

Category: Class Posts


Q1: A baseball team had won a game 19-17. No errors. But not a single man crossed the plate. How could this be?

A1: There are two solutions to this one…either every man that scored was married, or it was a women’s baseball team.

Q2: In the basement there are 3 light switches in the “off position.” Each switch controls one of three light bulbs on the floor above. You may turn on any of the switches, but you may only go up stairs one time to see which light(s) were affected. How can you determine which switch controls each particular light bulb?

A2: Turn on one light switch, leave it on for a few minutes, then turn it off. Then, turn a second switch on but leave the other off. When you go upstairs, one will bulb will be off and hot, another will be on, and the other will be off and cold!



Question 1 I like because it challenges the archetypes present in students minds. I see how gender roles are so embedded in student thinking, so when a potential solution has them thinking about female baseball players, I think its a good question. In so many classes that reference a scientist doing work, students (male and female alike) automatically make the assumption that the scientist is a male. Breaking this stereotype that science is a “guy” thing is an important part of  being a teacher.


Question 2 I like because it allows for so many different solutions, but the one listed is the simple and elegant one. For students that have not seen this question, I think they will be satisfactorily challenged to think about the implications of their actions outside of what is expected. The question simply says that the students needs to determine which light switch controls which light, which immediately makes the connection between light bulbs and radiative emissions in their head. Students must also consider that light bulbs radiate energy not only in the form of light, but heat. I can see a lot of students making a table (similar to how Tyler did in class) in order to solve the problem.

Preview Exam/Assessment

Q11: Answer = 4, not 3. I know its graph four because I intended to select graph four (it was the only bar chart that modeled the situation). Unfortunately I am quite possibly the silliest of all the gooses (geese?) and wrote down 3 because the formatting led me to believe number 3 represented answer number 4

Q13: Answer = 3, Not 0. As it turns out, “0” is not a valid response for questions number 1 – 5. 0 was the answer, however. Again it would appear that this error stemmed from silliness.

Q15: Answer = 3, Not 0. See reasoning above.

Q16: Answer = 4, Not 2. Or was it 4? I’ll double check with the answer sheet after this, as I’m currently typing this up while the 194 kids do their practicals. I forgot to take the total area under the curve. Rookie mistake. No silliness here, just pure amateur hour.

Q17: Answer = 4, Not 2. Same reasoning as above.


Attached is my redacted exam: Redacted_PUM

I figured instead of doing just one quiz I would get practice doing several daily assessments and then one open ended assessment question. I tried to give the students just enough information to make them think about all the different possible questions that could be derived from the little information they had.


Two screencasts covering How To Optics!

Youtube links are coming soon.


Youtube is silly. See below for Vimeo.


Here’s the Optics SMART Board activities! I’m very glad I chose this module, as it was very fun to make solutions to these. I also really like how the module steps students through how to build trigonometric reasoning abilities. This is an incredibly important skill that is glossed over, and students are left to just “get better” with it instead of actually being taught how to reason through problems.

Anyway, here’s the smartboard file.

Data acquisition

Rather than using logger pro, I opted for using my smartphone’s accelerometer.  I attached it to a vertical spring/hanger system and taped my phone (at the center of mass) to the hanger. From there, it was just a matter of setting the acquisition time and data file. Attached is the data, here is the graph after editing

Z axis acceleration vs Time

Z axis acceleration vs Time


I did some tricky analysis to make the period appear longer, just so it was easier on the eyes. The data is surprisingly consistent. I have included the excel file so you can the data pre-prettification. Its interesting to see the whole spread of the data collection.




Here this would be incredibly useful for students investigating the period of the object. Had they drawn force/motion diagrams previously, using the smartphone (since at least one student will have one at each group) is a quick, easy, and cool way of testing their models.


Dynamics 1.6

In the dynamics section there was a rather poorly drawn example of how to go from a freebody diagram to a force diagram. At first I thought this was intentional (so students could see an actual sketch) but after further reasoning I decided this was not an appropriate time to use a terrible diagram.

Energy 1.1, 1.2

I made this invention sequence (plus the following one) two or three years ago with pen and paper, then scanned. Obviously this left a lot to be desired. So I decided to rework these. Both the weightlifting index and the car washing index is meant to help students invent the idea of a product quantity. Hopefully these designs are clearer.


Created, Energy 1.7

There was a word problem in the energy unit where a cart sliding down a ramp had work done on it by a string, thus further increasing its chalk smashing potential. I decided this was in need of a diagram.


ReworkedInventionSequences <powerpoint >


Well, this was interesting.

For the qualitative testing experiment I made a pretty simple pendulum testing model. I have 3 pendulums with bobs of different masses but the same length, and then two pendulums with bobs of the same mass but different length. This is meant to qualitatively test the hypothesis  that the period of a pendulum is proportional to the length of the string/wire/linear-non-stretchable-object. If this hypothesis is true, then the 3 pendulums should oscillate together without collisions. This is true for small amplitudes, but for larger ones the relation clearly does not hold. File can be found here.

For the quantitative experiment, I again went with something oscillatory, this time with a mass/spring cart system. Students can measure the position vs time, and from that graph ascertain the period of the oscillation. By pausing and adding or taking away mass, students can determine how exactly period of a spring is dependent on the mass and spring constant. File can be found here.

For fun, I made something called Beware The Rainbow. All of us are well aware that Lord Unicorn Pegasus, enemy of the Robotic Republic, is a vicious creature that demands sacrifice once every thousand years as tribute for protecting our universe from invasion of synthetic life. Seeing as the last sacrificial ceremony in honor our lord and savior was 500 years ago, I created a short simulation…for posterity. Simulation of our future can be found here.



Geogebra 2

For the second geogebra, I wanted to do something cool, but quickly found myself limited by my experience with the program. I wanted to create a situation where students could see how Fraunhofer Single Slit Diffraction depended on slit width, wavelength, and distance to the screen, but ended up with a raw simulation only dependent on wavelength and distance to the screen. Ideally I would have added a wave function for the intensity as well, but that was beyond the scope of my abilities given my time constraints this week.

Instead I used a ray model, with a slit width of one micrometer. The distance varies between 1 and 2 meters, and the wavelengths vary from either edge of the optical spectrum. It serves the purpose of allowing students to get a qualitative feel for how maxima and minima vary based on what kind of light is shining through and how far away the screen is, but I really would have liked to add intensity. 

I couldn’t figure out how to rotate the sine function (rotate object about point didn’t seem to work), but in the future I suppose I could feasibly just rotate my canvas and laser instead. 

Obviously this would work well for a class on optics, with the goal of having students feel their way through how light diffracts. PUM did not have a module laid out for optics, so this one was a bit of a solo project.

Here’s the link

Geogebra 1

It took me a while to think of something do simulate, and eventually I settled on making a variable force diagram for a pendulum. About 20 minutes into this, I decided that this was a terrible idea and set out to create a more interesting variable simulation. I stuck with the pendulum idea, but instead made a bar chart in geogebra.

This is modeled after the Energy Module in Pum, Lesson 3.4 specifically. Students are asked to reason as to how bar charts would change given different points in a bar charts motion. This simulation allows students to instantly check their reasoning.

Making the simulation was straightforward enough, from the get go I knew exactly what I wanted to accomplish. The hard part (unsurprisingly) was figuring out how to get geogebra to do what it was that I wanted it to do. You’ll have to forgive my work, as it is a bit messy, but lo and behold I accomplished my task.

A few notes: I made sure the pendulum bob was bound to the arc length cut out by my pivot point and two anchors, but for some reason it keeps going to a height of 1.01 instead of .98 on the right hand side. Because of this, the Kinetic Energy shows as (slightly) negative on that side. I’m not entirely sure why geogebra is allowing the bob to exceed it bounds on the right hand side, but seeing as this doesn’t really take away from the main point I’m not too worried about it. In addition, the simulation is not mobile, it is bound to the x-axis (technically it is mobile, but I wasn’t clever enough to design it such that all measurements are relative). For fun, I added two sliders: one for the mass of the bob and one for the value of the constant “g”. I imagine students will be able to have fun checking to see how messing with these values will affect the graphs.


Here’s the link.

Mail Merge 2

For the second mail merge, I decided to contrive an electrostatics quiz. The challenge here was deciding what values would lead to realistic results for the students. I really went all out and have large variations in all of the different value fields, so I don’t think any two quizzes are exactly the same. For the question that asks students to solve for conditions of a new acceleration, I decided to just take the answer to the previous question and add two onto that magnitude. I will be able to quickly tell whether or not students got the correct answer that way.

On one of the quizzes the sum of forces is 0. I purposely left this in, as I do not think it is too much to ask students to use their critical reasoning abilities to realize that when the sum of forces is 0, acceleration is 0 and the mass of the object of interest is completely irrelevant.

This quiz is similar to to Electrostatics Quiz 3 CP, question two.

MailMerge2 – Quiz Setup

MailMerge2MERGED – Merged Quizzes

SMITH_MM_project – Value fields listed under “Mail Merge 2”