Pivot Interactives - these videos are so worth the money.

Screenshot from Pivot Interactives

As you might have noticed, my all-time favorite internet physics resource Direct Measurement Videos has migrated.

Vernier now is selling access to "Pivot Interactives", for $150 per year or $5 per student, whichever is greater.  On one hand, I wish the National Science Foundation had stepped up with a seven-figure grant for primary DMV creator Peter Bohacek so that he could continue to provide these resources free to physics teachers.  I mean, I can list probably 10² NSF grants that flush my tax money down the toilet. Nevertheless, I'm happy that Vernier has seen the extraordinary value in these exercises to keep them alive.  

The question for the physics teaching community is, then, do we spend the couple hundred beans to get access to Vernier's new site?  For me, the answer is definitely "yes."  

I've made it my official teaching goal this year to replace as many textbook-style homework problems as possible with Pivot exercises.  Since Peter and company have been hard at work adding to their video library, I'm finding this goal easy going.

Take, for example, the car-around-a-traffic-circle problem.  I've always started my circular motion unit there, as it's a situation all my students have experienced.  I ask, how fast can the car go around the curve?  We discover that the maximum speed depends only on the curve's radius, g, and the coefficient of (static) friction. 

Great.  But this is an abstract "imagine if" problem.  I can't take my students to a traffic circle for experimentation - the nearest one is 20 miles away, and is too busy for fooling around, anyway.  All I can do is suggest that the yellow suggested maximum speed signs don't include a mass variable - they say "max 25 mph", not "max speed in mph is 0.025 times the mass of your car in kg."  Interesting... but not experimental.

Well, look at the screenshot at the top of the post.  Peter took his drone to a traffic circle.  He drove the gray car around the circle at a speed that was always on the verge of slipping.  When he imported the video, he included tools to find angles around the circle, the radius of the circle, and a frame-by-frame timer.  I can't do this experiment, but Peter can. And did.

So for a homework problem later in the circular motion unit, I link the class to this Pivot Interactives video.  The site allows me to customize the assignment - the default is quite good, but I can add or eliminate questions and guidance.  For me, I like a clean prompt like "Determine the (maximum) coefficient of static friction between the car's tires and the ground."  The site allows students to input their solution and reasoning directly in the space provided; you can then scroll simply from one response to the net, awarding points if you'd like.  I prefer to have students answer on paper, but that feature seems to work as well (paper not provided by Vernier).

There's so much more that Pivot does.  I prefer the simple open-ended "determine this parameter" exercises.  But Pivot also has some modeling exercises, providing an easy graphing interface that allows students to make and linearize plots.  These multi-layered videos allow you to change multiple parameters.  The prompts guide students through what essentially is a complete lab exercise which you might never be able to do in your own classroom; or, a lab exercise you don't have the time to do in your classroom but can assign for homework.  I know that Vernier has gotten some serious physics teaching experts, including Kelly O'Shea, writing these exercises.  

And Peter is adding videos every time I look.  

Look, I know it's disappointing to have to pay for what had been available for free.  And I generally don't recommend paying for physics content on the internet.  Nevertheless.  

Vernier has hired the varsity for this project.  Everything I see on the site is something that makes me say "wow."  Pivot cannot replace a physics teacher doing active lab work in the classroom, because nothing can.  Using Pivot gets students as close as I believe it is possible to come to an online laboratory experience.  I highly recommend.

GCJ

(Note that Peter and Vernier have not paid me in any way for this endorsement.)