I’ve been teaching a semester long electronics class every semester since I started teaching in 2000. It started as a basic circuits course, but several years ago I started teaching it with the Arduino micro-controller platform. It has undergone several transformations over the years and I’m changing it yet again this semester.
We’re starting with some basic circuit fundamentals. In the past I assumed they would learn these fundamentals as we worked with Arduino. It turns out I was wrong. One of the circuit building things we did this week involved making paper circuits. This worked out really well and gave students a chance to discover differences between series and parallel circuits. They also got to do some trouble shooting to figure out closed, open, and short circuits.
All in all it was a fun project to help set the tone for the semester while also giving us an activity we can refer back to as we move forward.
We have a new chemistry teacher this year. At his old school he used these conductivity meters from Flinn Scientific. He said they work really well. He had students use them to make qualitative comparisons of the conductivity of different solutions. The only problem I saw was their price tag. They are $22 ea. This is not horrible, but there really isn’t much to them. So I decided to see if I could make them cheaper.
Turns out it was pretty easy to source the components to place the cost at no more than $1.50 ea. So, for the price of one of Flinn’s meters I can make a classroom set.
I created a set of instructions for making your own: Conductivity Meter Tutorial (PDF)
I used Plasq’s ComicLife to create this. I’d forgotten how much I enjoy using this for making tutorials.
Tomorrow, Saturday 10/4/14, is the fall meeting of the Michigan Section of the American Association of Physics Teachers. If you’re interested, it will be at the University of Michigan, Flint. For more information you should check out the meeting page.
Anyway, Jim Gell and I will be running a Make and Take in the afternoon. One of the things we will be doing again is the ever popular LED Color Mixer. We’ve done this before as a modified version of the LED mixer presented by Chris Chiaverina in the Physics Teacher
. This is a pretty cheap demo device, but in the past we ordered $1-2 LED, $1 battery holder, $0.50 ping pong ball, and 2 AA batteries. Cost for each one was between $3 and $4. This was a bit costly to run as a Make and Take. It also involved soldering, which while not particularly difficult did require the direct supervision of someone.
We will be doing the same project on Saturday at a cost of less than $0.20/device with no soldering required. This project is cheap enough that you can have participants make one on site and then send them home with a couple extras to make with their classes. They’re so cheap that a teacher could have each of their students make one to take them home and explain how they work to their families.
I should note that while both the batteries and LEDs are sourced from Amazon, the LEDs come from China and will take a few weeks to arrive. While the LEDs are cheaper than we’ve been able to get them in the past the real savings is from the batteries. In order to make things extra cheap I replaced the ping pong ball with a paper cube.
Simply bend the leads on the LED as shown. The shorter of the two leads goes to the negative side of the battery with the longer going to the positive. Use a little electrical tape to hold the leads to the battery. If needed, slip a small strip of overhead transparency in between one lead and the battery to act as an “off switch”.
Print out a copy of the 2.25″ Cube Template
and assemble. Before closing the last flap put 1/2 a Kleenex in to help diffuse the light and cut a hole in one side. The simply slip your LED and battery in and bask in the color changing goodness you have created.
How would you use this with your students? Share your thoughts in the comments.