SMS Clickers

I’ve been incorporating “clicker” questions into my physics classes this year, and so far I would say it’s been a success.  There are ups and downs while using them, but overall the process is working pretty good.  However, yesterday’s class really got me thinking about how to optimize my process.

First of all, here is a brief on how I use clicker questions in class.  We don’t have clickers.  Instead, I’ve been using Poll Everywhere.  In the school where I’m at, almost all of the students have cell phones or smartphones with text messaging plans.  This allows me to use Poll Everywhere and have 100% participation.  For the couple of students that don’t have a sms plan, they are instructed to find a friend that will vote for them.  If that doesn’t work, I say that I will enter a vote for them.  The other key to my use of Poll Everywhere is that I run two computers at the same time, monitoring the polling.  My tablet PC is projected to the students, and it only shows the voting questioning and instructions on voting.  My desktop PC shows me more controls and the actual polling results.  When I first started doing using Poll Everywhere in class, I was showing the students the poll results in real-time.  This didn’t work very well, as the students seemed to be strongly influenced by the poll trends they were seeing.  Other than using sms polling vs. clickers, the method that I use Poll Everywhere is the same as Eric Mazur’s Peer Instruction.

As mentioned, this system is working ok.  Yesterday in my classes we had some good discussion on a question where a person is in an elevator accelerating upwards and it was asked which was greater: the normal force acting on the person, or the person’s weight?  This question had followed the introduction of Newton’s 3rd Law, which tells us that for every action there is an equal and opposite reaction.  I had warned the students that Newton’s 3rd Law is very tricky in application, and this poll question demonstrated this.  The polls were pretty much split 50/50 between the normal force being larger (the correct answer) and the normal force and weight being the same.  Much to my surprise though is that when I had the students discuss the answer and vote again, almost everyone voted for the forces being the same!  Obviously I had hoped for the opposite to happen, and I need to check with Mazur’s book again to see if he addresses the case that peer instruction delivers a overwhelmingly incorrect response.

As a bit of an aside, this question did a good job in revealing a misconception.  Many students believed that a bathroom scale always measures weight, when in fact a bathroom scale measures normal force.  The other really positive outcome from this question is that it tied in really nicely with my protheselzing that all dynamics problem solutions should include a free-body diagram.

As for the polling method itself, there was one thing that really surprised me.  I’m not really getting anything close to a 100% response rate from the students.  At best it is about 75%.  There is still a reluctance from the students to vote because they are unsure of the answer, even thought they know it is anonymous.  More annoying to me is that I can see the students are just kind of lazy.  Some of them have their phones tucked away in a backpack, turned off, dead battery, etc.  I do like the sms polling better than showing flashcards though. I think the annonymous aspect of voting is very important, and I really like that data collection aspect, as opposed to counting flashcards.

While the sms polling is good, I would still like to improve the process. I think that if I actually had clickers in the classroom, the immediacy of pressing a button would greatly increase the response rate.  This in turn would help the streamline peer instruction cycle.  Waiting for kids to get their phones out, turn them on, squint at the instructions on the screen (I don’t have a very large projection screen) all slows the process down.  I can’t imagine getting a budget for clickers though, and a classroom set would probably cost about $1,200.  Another idea would be to ask the students to place their phones on the desk at the start of class, and this would help streamline the polling process.

For now though, the Peer Instruction and Poll Everywhere are a success and it will be interesting to see how the level of engagement goes up or down throughout the year.