Introduction: LED Quizboards

Looking for a way to incorporate simple circuitry into other parts of your teaching day? I am amyfitz1, and I have run an Outreach program at the Edgerton Center since 2001. I have led multiple sessions for students using Quizboards to showcase their abilities in geography, foreign language skills, book obsessions, sports' team allegiances, and other amazing trivia (egg-laying cycles of most common backyard chickens anyone?). While I generally have a particular set of materials in stock that I use with my classes, I made a point of using materials that I had around the house for this explanation.

Supplies

LEDs, 3V coin cell battery (or two AA batteries), wires (or copper tape), conductors (we used paper clips, could easily be paper fasteners, maybe metal buttons), wire cutters/ strippers, needle-nose pliers, scissors/ craft knife/ nail, cardboard base, electrical tape (optional)

Step 1: Preparing the Materials for the Circuit

First, grab a number of through-hole LEDs. (Longer pins are easier to work with.) Remember that the polarity of the pins (negative v. positive) matters. You can color-code the pins (red for positive or black for negative) with a permanent marker, but you don't have to. I opted to bend the LED leads in two different ways to remind me which was which. For the negative lead, which I was planning to push through the back of the board, I wanted the wire to lie flat. Using my needle-nose pliers (by hand would work), I bent the wire into one flat loop. (Remember, the negative lead is the shorter of the two; it is also next to the flat edge of the LED collar.)

For the positive lead, which was going to remain, like the light itself, in the front and visible, I used my needle-nose pliers (okay, I cheated and used the ones that are for jewelry making, I think they make nicer coils) to twist up the wire into a nice, tight bundle of loops. These I bent so that they would not lie flat on the board, but would stick up. This is helpful, since I planned on closing the circuit (connecting the electrical connections) by 'catching' the LED lead with a paper clip.

Before I went ahead attaching ALL of the LEDs to my board, I wanted to test that I had them set up correctly, so I next wired up a battery.

Step 2: Testing the LEDs & Battery

This is an exciting step, since you'll get proof of your successful circuit-building skills!

If you have a coin cell battery (like mine) you may not have an official battery holder (I didn't). I cut two lengths of wire, each 12-24". Decide on a length by considering how large your board is, and where you plan to attach the battery. If you'll be "hiding" it on the backside of the board, you'll need more wire - simple. I used 22awg stranded wire, with red for positive, and black for negative. I used my wire strippers to remove .75-1" of insulation off of each end of the wires, and then twisted each end to tame the strands into one unit.

Since I didn't have a battery holder, I coiled and then taped one end of each of the wires to correct side of the battery. Make sure that the exposed wires don't touch each other or the opposite side of the battery, either of which would short circuit the battery. The two free ends (+ and -) can now be used to test the LEDs; the lights will only illuminate if the red wire connects to the positive LED lead, and black wire to negative. I looped each of the wires to a bigger size paper clip, just to have something to hold that wasn't floppy. Think of it as a pointer, or handle. Twist the wire to one end of the clip, making sure that you are twisting the metal part of the wire to the clip. You can cover this with tape (doesn't have to be electrical) to keep the connection firm.

If the light doesn't work, re-check connections but also try flipping the LED (super easy to mix up the + and -, especially when the leads are bent). Fix what you need to. You can also check whether or not you have the LED colors you intended to grab. (My LEDs are all clear when not powered.)

Be nice to yourself and attach the battery somewhere to the board; right on front is just fine. Its not fun when you're ready to try this out and suddenly the battery is gone!

Step 3: A Topic for the Quizboard

Time to set up the content of the Quizboard.

I prefer having the questions on one end of the board, opposite the answers. If you're opting for multiple choice or true-false questions, your board will probably look more like a grid. I have all the labels written in the bottom left corner, with my diagram filling in most of the center and right side of my board. Make sure that your questions and answer labels are far enough apart so that when the LEDs and paper clips are added, the conductive parts will not touch each other accidentally.

You'll need to have your collection of LEDs and paper clips that mark both the question and answer locations on your board. Make a small slice through the board where each question and each answer is located. I've recycled the packaging of a soda 12-pack, so the cardboard is pretty thin, and a craft knife or even scissors would work. For thicker (corrugated) cardboard, you may prefer using a nail (no hammers!), and enjoy the lovely 'pop' sound you get as you pass through.

Pass the negative twist of each LED through one of the question spaces; and clip a paper clip into each of the answer spaces. This should give you some metal showing on the front and also some passing through to the back. Check for any accidental touchingon either side!

Step 4: Setting Up the Board

All of your questions are on the board, answers too! Time to "teach" your board which answers are correct. Are some of these trick questions, with more than one right answer? No problem! Time to determine what your needs are in the wire vs. conductive tape question.

Usually, I like to draw a "map" of which question connects to which answer; this keeps me from having to redo any wire connections (which is next!). Draw a light line on the back side of the Quizboard connecting each match. Take. Your. Time. If you have lines that cross, you should stick to wires rather than conductive tape.

Time to add the wire. I use either stranded or solid 22awg wire for this (stranded in this example), and like to measure each piece before wire stripping and attaching. You'll want a length of wire that not only reaches from the question to its answer, but leaves an extra inch of wire at each end.

Get your first piece measured, then cut, and then time for more wire stripping! You'll want to strip an inch of the insulation off of each end (do both ends before attaching, it'll be easier for you). I have looped the metal part through the negative end of one of my LEDs on the backside of my Quizboard. To make a good mechanical AND electrical connection, do your best to make your twists so metal is touching metal. Do this for both the LED end and the paper clip end. This will complete one of your circuits. (I don't usually use electrical tape for this. Neither the end pieces nor the wire connecting them should be moving, so they are unlikely to disconnect.)

Repeat for each question. Multiple correct answers = multiple wires.

Step 5: Test It!!

What are you waiting for? Try out each of your questions to make sure that the lights respond to the right answers. Touch the red wire clip to the positive lead of an LED, and at the same time, touch the black wire clip to the answer. It should glow! (IF it doesn't, double check that the battery is still attached to the leads, then also double check that the wire is still attached, and THEN make sure that the wire is attached to the RIGHT answer.)

Does it all work? Great! Go find someone to share the gift of your Quizboard with!!

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