This Fall I used an app called Vernier Video Physics with one class, PHYS 1101: Physics for Life Sciences. I joined the project partway through the term, so this is my first post. We used the app in two contexts; it was introduced in a lab, in which student groups needed to get qualitative results for the oscillation of a pendulum and the rotation of a turntable; and in a student project, to be done outside of class during the last few weeks of the term, then shared with the class in a sharing session during the last week.
The app itself is well-designed and has tremendous potential to allow students to make visual records of motion, which can be analyzed both qualitatively and quantitatively. Motions can be observed wherever they can take their iPhones: a basketball game, hockey game, the playground, a store, their own back yard, etc. Briefly, the app enables the user to take a short video (typically a few seconds) and plot frame-by-frame the position of a point on the object of interest (ball, puck, etc.). The app then produces graphs of motion (position vs. time, in two dimensions, x and y, and velocity vs. time in those same two dimensions). These graphs can easily be analyzed to determine things like the acceleration of a falling object. This enables users to answer questions that are often not asked in a class at this level, as students do not have the mathematical tools to answer them; for example, if we drop a ping-pong ball from a 3rd-story window, does it accelerate uniformly as it falls, or does air resistance change the acceleration as the ball falls?
You can get an idea of the app from this site: http://www.vernier.com/products/software/video-physics/
Device and app availability
About 1/3 of students had iPhones. I reimbursed them from lab fees for the cost of the app ($3). I put our two Physics Dept iPods in IMS for loan by my students. The Langara library will be loaning out iPads soon, and I will investigate putting the app on these.
The lab
During the time we were studying oscillatory motion, I assigned groups of three around owners of iPhones to do two qualitative exercises as well as some quantitative work. Two departmental iPods and an iPad were loaned to groups without an iPhone. The first qualitative exercise was to use the device to video the swinging of a pendulum, then view the graph of motion (x vs. t) to determine if qualitatively it looked like a sine function. The second exercise was to use a sample video, included with the app, to plot the x vs. t and y vs. t graphs for circular motion (the sample video showed a point on a record player turntable as it rotated). These graphs, too, were to be compared with sine functions (which they are!). All groups successfully used the app for the intended purposes, some with help from me.
The project
The second context was a project, in which students were asked to capture and analyze a motion relevant to any of the topics studied in class, then share their results with the class. The instructions are below. A majority of students, attracted by the bonus marks incentive, elected to do this optional project. However, I was disappointed in the lack of creativity shown by student groups. I had hoped that these students, being self-identified as “life-science students” would do something biology or human-kinetics related; perhaps record the jumping of an animal, even a pet; the acceleration of an athlete; or a sports motion. Most did the easiest thing possible, videoing a projectile, and not even leaving the college to do it. One group came to my office to ask to borrow a ball, then made a 2-second video in a neighbouring classroom. One group videoed a basketball shot in the gym (almost identical to one of the sample videos provided with the app). One group videoed the motion of the pendulum of a grandfather clock, much like the exercise done in the lab.
Displaying the videos in the sharing session
I borrowed a VGA cable from EdTech to connect the iPad so it could be displayed on the podium system in a smart classroom. This worked for the iPad but not for the iPods or iPhones. So instead I used a Physics department Elmo video recorder to display all devices. This worked quite well and was a very easy solution: the Elmo sat on a desk, and students slid their device into the field of view to show their videos and graphs. The app allows videos to be uploaded to Facebook, so next time I would like to set up a closed Facebook account for the class, so they could upload their videos before the sharing session. Then all videos could be shown and discussed in the sharing session in a smart classroom.
Changes for next time
· I would set up a Facebook account for sharing
· I would prepare one 2-hour lab as a training session on use of the app, with several exercises
· I would develop a rubric which rewarded creativity, off-campus video locations, and biological relevance.
· I would assign a variety of different projects to different groups, perhaps randomly, so that we wouldn’t have too many groups doing the same thing.
The Project Instructions
PHYS 1101 Video Assignment
This assignment is optional, not required. If you choose to do the assignment, you will need to agree to show your video, and discuss your graphs and analysis in a sharing session during the last week of classes. As an incentive, I will offer a bonus of 3% of your total grade to anyone completing the assignment successfully. You may work alone or in a pair or group of your choice, maximum three students.
Assignment: analyze a video taken at the college or elsewhere using the Vernier Video Physics app, or using a digital camera video uploaded to Logger Pro on the physics lab computers. The video should relate to the concepts covered in class. Some ideas are below; see me if you would like to discuss others.
Hardware and software requirements:
- Your own iPhone, iPod or iPad — use Vernier Video Physics app. If you have not yet downloaded it, do so and show me in order to get reimbursed the $3 cost.
- College iPod — borrow from Instructional Media Services (IMS) in room C265 (access this room from the 2nd floor of the A Building; IMS is just around the corner from the Chemistry offices). Day loan or overnight loan is possible. Overnight or weekend loan requires my signature.
- Your own digital camera — use a cable or memory card-reader to transfer the video to one of the Physics lab computers, then import the video into Logger Pro and analyze. Then transfer to a memory key for sharing in the classroom.
Tips for taking a useful video:
- Do not pan; keep the camera still for the entire shot.
- Make sure motion is in a plane perpendicular to the camera — ie., a ball coming towards the camera will not work
- Make sure there is something in view that you know the size of, for scale. Could be a person whose height you know, or a doorway, or another object.
A few video ideas
- projectile motion: throwing a basketball, throwing a volleyball, passing a football
- impulse-momentum equation: shooting a puck, hitting a tennis ball, batting a baseball, kicking a soccer ball; impact of pool ball with side of pool table
- free fall and drag: drop a ping-pong ball or other light object from a high window, then measure position vs. time on the video (you definitely need two people for this one)
- Acceleration and force for a jumping dog, cat, gerbil, frog, grasshopper, etc.
- oscillations or rotational motion: use playground equipment, or maybe a video you took at Playland last summer…
After taking your video, see me for help with analysis.
Sharing: Use a memory key to save your Logger Pro file from a lab computer. You will need to show this in class during the last week. It is also possible with the Vernier Video Physics app to upload to Facebook. Physics has a Facebook account but we haven’t worked out the details yet.
Robin Macqueen, Physics & Astronomy Department