I am so stealing this. I mean, using it with proper credit given.

That is excellent video editing work.

I would have ended up putting 20 individual stop light videos. This is why you are the master and I am but the learner.

Someday the circle will be complete.

Taking down the man. That is the kind of project I like.

“At their twenty-year reunion, will your students remember their investigation of cylinder surface area or the time they brought down city hall?” – So true. My students still talk about the Applebee’s lesson, and I’ve had parents bring up how much their kid loved calling Applebee’s and making a scene. It makes you feel like you’ve done something right.

Beautiful idea.

Great stuff, as always, Dan.

A little frightening how many readers you have with father issues, however. Hard to believe that in the United States of America, so many people can be roused by the phrase “sticking it to the man.” My couch is now [OPEN].

More seriously (well, I wasn’t completely kidding above), this seems much more on point than the Applebees lesson. Nailing government at the highest level appropriate when it is either dishonest or simply incompetent in its efforts to squeeze money from its citizenry is a noble task, on my view. Dropping this sort of data on the desk of the mayor (or the head of the traffic department or the agency that collects fines for violations, etc.) puts the ball squarely in the court(s) in which it belongs. Sending the same report to the local media pretty well guarantees that things won’t get buried.

Sure, there are similar things going on in the corporate world, but if you’re going to complain, I think it should NOT be to small fry (wait staff, local managers of restaurants, etc.) who have no say in the slogans of their corporate masters and no time to check on their veracity or lack thereof.

And yes, I get that kids are motivated by “sticking it to The Man”: I just want to be sure that they are actually doing that rather than blowing off steam to some poor schnook who is just trying to eke out survival wages at a local franchise.

Math as part of raising social consciousness and appealing to the social conscience of people in a position to make change is a wonderful idea (and of course likely to tick off parents and others who don’t think that’s what school is supposed to be about – something that could provide many valuable lessons in civics in itself). But let’s not go off half-cocked with the notion that as long as we’ve found inaccuracy in public or private life that we should jump on the nearest person connected in any way to it. “Beating up on” workers isn’t exactly the way to accomplish the changes I’m sure we’d all like to see. Making things hot for the real bosses, however, is another matter entirely.

An interesting book to look at in connection with all this might be Terry Southern’s THE MAGIC CHRISTIAN (if you can get hold of it). I love Guy Grand and his wicked propensity for “making things hot” for people. But I’m not sure all his targets were well chosen (too long since I last read it). Always worth taking a moment to think first.

Great idea! I do this sort of thing a lot in my classroom. This summer I was summoned for jury duty and I came up with a ton of questions and probably a 2 day lesson and exploration that I will do with my students. (And I wasn’t even chosen for the jury!)

Mind if I use this? I’ll send my other ideas your way. They involve creating a water tower for the new high school being built, creating a schedule with times and songs included for the local hit radio show, and many other ideas that are currently locked in my classroom.

Whether sticking it to the man or not, I love traffic stuff. So here is a half-baked idea I used in a workshop once, and it really worked. Appropriate for drivers:

You’re sitting at a red light and thinking, “Man, this light is badly timed. We shouldn’t have to sit here this long.” You may even know an intersection near your house or school that you think is particularly horrible.

So apply the eternal measurement question: how bad is it? [Possibly working with a group] figure out a way to compute a number that measures how well or poorly a light is timed based on observations you can actually make at the intersection. Use your technique to compare intersections with one another and make an argument that your way does or does not reflect actual traffic light well-timed-ness.

For example, one group counted the number of cars that were stopped, waiting to go when the light turned green, and compared it to the number of cars that got through the intersection in a whole light cycle.

That in itself was kinda brilliant–finding something reasonably easy to count that could be translated into what you’re trying to get at–but then you get the symbolic-math payoff when you have to describe to others how you combine these numbers to calculate your index of goodness. All kinds of issues come up. Difference or ratio? Ratio of what? How do you make a good intersection get a larger number? Should a good intersection get a larger number? How well does the number translate from one intersection to another with more overal traffic–does it make a fair comparison?

Any chance you can share some tips on how in the world you made that freaking awesome video clip?

Any ideas for what unit(s) this activity could be incorporated into a high school Algebra II class? I love it!!!!!

I think I’m going to use this in my physics class, just after we’ve learned about acceleration. That’s the straight-forward project that you’ve suggested – and it’s a solid one.

But from my experience as a crash researcher, it seems that there is greater depth in using statistics. Present the issue of red-light cameras – are they for safety or revenue? Do a public records request (or see if NHTSA has data) on injury & non-injury crashes at those intersections. Do the red light cameras actually reduce the incidence of crashes? I know you can find the revenue from newspaper articles in most major cities, because this has been such a hot-button issue. The red-light timing can be another aspect to add to this project.

I think the project you described on timing of yellow lights is great. Here’s something related that I’m considering pursuing.

In my community, many of the street lights are being replaced with LED lights. It’s easy to understand the motivation in terms of energy saving (http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/question178.htm), but I have noticed that a significant number of the LEDs fail (leaving sometimes interesting patterns).

I’m considering gathering data on one conjecture: LEDs of green lights fail significantly more that yellow or red. I believe this is true and the reason might relate to the amount of time green is on but it might also be color related (physics connect?). Also, if in fact the failure rate is as high as it seems (I think almost all lights in my community now have dead LEDs), is the energy savings commensurate with the replacement cost?

An video of an LED traffic light along with an interesting observation from Holland about LEDs not melting snow can be found at

This activity is fantastic, and similar to one that I do with my Physics class each year. We usually just do it with the one traffic light outside our school, but this year I’ll try sending students out to track other intersections and see if we can compare intersections that have cameras with ones that don’t. Such a nice extension. And my students will sure love to “stick it to the man” if they find a difference!

The activity that Frank Noschese linked to is a lot closer to the Yellow Light Problem that I do with my students. I’m not sure how light times are set over there, but if the article is correct that “according to county guidelines, yellow lights should be on one second for every 10 miles per hour of the speed limit”, that doesn’t sound very safe to me! A safe yellow light time depends on both the speed limit and the length of the intersection, as it has to allow people to stop safely before the intersection AND to clear the intersection safely if they’re beyond the safe stopping distance.

From my course’s assignment:

“The Ministry of Transportation of Ontario (MTO) Traffic Branch Manual of Uniform Traffic Control allows for a REACTION time of 1.0 s for city driving and 1.8 s for provincial highways, where the speeds involved are greater.

The BRAKING time is the time it takes the vehicle to come to a full stop once the brakes are applied. This time depends on the initial speed of the vehicle and negative acceleration of the vehicle. The MTO-predicted braking times are based on the assumption that vehicles are travelling at the posted speed limit and, for most purposes, the MTO uses a uniform acceleration of 3.0 m/s2 [back].”