Video Analysis with Pivot Interactives
We’ve heard from many physics teachers who want better tools for students to analyze their own videos. The top features requested are:
make it easy transfer video from cell phone camera to video analysis app
allow analysis on all platforms: iPad, Chromebook, Mac, and Windows
make it easy to add calibrated rulers, grids, and protractors for measurements.
provide a way for teachers to grade or give feedback on the video analysis process
Teachers are our most important source of feedback for making improvements to Pivot Interactives. We’re happy to say that we’ve created new functionality in Pivot Interactives that meets all these requests.
Both teachers and students can upload video either from their cellphone, tablet, Chromebook, or laptop directly into Pivot Interactives video analysis with no file conversion needed. After the video is uploaded, students can do the analysis on any device. As with all Pivot Interactives activities, teachers can provide feedback or grades at any point in the process.
Our new calibration tool make it easy to calibrate the rulers and grids to match the scaling object in the video:
stretch the calibration tool to match the reference object in the video
type in the calibration size and units
now all rulers and grids will be automatically calibrated to match the video
Once the video is uploaded and calibrated, students use the rulers, grids, protractors, and stopwatch to make measurements. The integrated data tables and graphing allow students to analyze their data immediately. Teacher instructions guide students. Student work is automatically saved as they go, and the teacher can view, comment or, or grade student work at any time during the process.
Many teachers tell us they want their students to analyze their own videos. But they also say that the apps available either take too much time, are not compatible with their devices, or lack the features they want. With these new video analysis features in Pivot Interactives, teachers have a tool that does what they want.
You can learn more about how these tools work on our documentation here.
While testing these new features we did a lab this week where students recorded a video of an object sliding along a surface, being slowed by friction. Students uploaded the video to into this activity in Pivot Interactives, and collected data to make a position vs time and velocity vs time graphs. From there, they determined the acceleration of the object and used it to find the coefficient of friction between the surface. Within one class period, (nearly) every student had a video uploaded and had created a velocity vs time graph. Here is an example video showing a van skidding to a stop on an icy driveway.
Here’s the velocity vs time graph from this motion. Notice how the acceleration is nearly constant. Students were asked to use the shape of the velocity vs time graph to determine whether the friction force is dependent on velocity. In most cases, student’s graphs showed acceleration that was constant, but some seemed to show variations perhaps due to irregular surfaces or deformation of the surfaces.
Students clearly enjoyed this lab. They said it was interesting to see how all the techniques we’ve learned all year can be applied to something relevant to their lives.