Introduction: Classroom MP3 Quiz Board

About: I used to teach middle school science, but now I run my own online educational science website. I spend my days designing new projects for students and Makers to put together.

As former teachers we're always on the look out for engaging classroom activities. We recently created a large interactive Sound FX wall that we thought would be great for a classroom... until we realized that most classroom don't have a giant empty wall around. We then turned around and made up a desktop version that ended up being amazing for student interaction.

At it's core the project is a 'touch to play music file' project. On the most basic level it's a simple tool for learning vocabulary or for learning foreign language. Expanded on it becomes a great tool for student creation by having kids create their own sound files and graphics to go with it!

In this guide we're going to show you how we made this project, an example lesson we made up, and then several lesson plans for different types of classrooms. This project is simple enough that it can be made by any teacher and is age appropriate for both young and old children.

If you like this project and want to see more of what we do, check us out on instagram, twitter, facebook, or youtube!


Brown Dog Gadgets does in fact sell parts and kits, however you in no way need to buy from us to make this project. Though buying from us does help us continue to create awesome projects and teacher resources.

Electronics Parts:

Crazy Circuits Invention Board

Crazy Circuits Screw Terminals x 2

MP3 Playback module (This listing works, we've found that there are some bad modules floating around amazon.)

Micro SD Card (smaller and cheap) and adaptor/ reader

Male to Female Ribbon Cable

1/8th Inch nylon conductive Maker Tape

USB Cable

Powered Speakers (which you probably have around your house, or just buy these, or you could even use headphones if you wanted)

Craft Supplies

LEGO Base Plate

LEGO Plates

Poster Board/ Foam Board/ Cardboard

Self Sticking Velcro or other adhesive


A computer with a built in microphone to record audio

Step 1: Use Cases for the Classroom

This project is very modular. It can handle between 1 and 9 different inputs/ sound outputs. Since we're using conductive tape this project can be attached to pretty much any surface; glass, poster board, concrete, drywalls, floor tiles, and even fabric. At the tape endpoints it can be attached to any conductive material (though we're just using more tape) as a 'touch point'. These include conductive dough, conductive paint, aluminum tape, balls of foil, chunks of metal, or people. The way we have our code written up, the sensitivity of the 'touch points' can be increased so that activation can be done THROUGH a piece of paper or a vinyl sticker, allowing graphics to be easily changed.

Since there are so darned many applications we figured it would be nice to lay out a couple of options.

1) Interactive Wall

We recently posted a large write up on the wall we made in our office. This allows a very large and kid friendly format. Conductive paint can be used to make large, permanent 'touch points' or you can make large 'touch points' out of aluminum tape or more conductive tape.

2) Single Touch Point for Word of the Day, Question of the Week, Challenge of the Week, or Fact of the Week

Using an interesting object, such as a metal figure or fun graphic, a teacher could create a weekly changing sound file for their classroom. This could be as simple as a 'Word of the Week' or as crafty as a 'Riddle of the week.' Students could also create the sound files that go with this.

3) Desktop Quiz Board

This is pretty much what we're doing in this write up. On a large piece of Poster Board or Cardboard create 4-6 touch points. Overlay pictures that go with sound effects of your choosing, or have students create their own sound effects.

4) Music Player

Since the module we're using is just a simple MP3 player you could load it up with fun music files for your classroom. For teachers of younger elementary school kids this would provide a fun way to play music during different parts of the day, or signal changes in the classroom. It could be placed somewhere that would be easy for both the teacher and students to take part operating it.

5) Quiz Show Buzzer

Our code allows for preset delays between sounds being triggered, which means it would be a very simple task to turn our project into a simple quiz show buzzer. First person to touch their 'touch point' would have their groups sound effect go off.

6) Pop Culture Wall of Insanity

Use pictures of popular kids shows to play sound effects from that show, driving you slowly insane but providing a lot of joy for the kids.

Step 2: Assemble Your Circuit Board

Crazy Circuits components are designed to fit onto LEGO. We're going to use a LEGO Base Plate and some 1x6 LEGO plates to create a platform to connect parts together. Yes, we are making a LEGO circuit board using conductive tape.

Use some flat plates and lay out your pieces. We need to connect two screw terminals to the Invention Board in order to hook up ribbon cables. One Screw Terminal needs to connect to the 5V Positive hole as well as the Negative hole on the board, the other Screw Terminal needs to connect to Pins 9 and 10.

We're using 1/8th inch nylon conductive Maker Tape to make these connections. Once in place, screw in the male sides of your ribbon cables. The connect Pin 9 to the TX and Pin 10 to the RX on the Mp3 Module. The Positive and Negative junctions match up to the Positive and Negative pins on the Mp3 Module.

Why are we using the Crazy Circuits Invention Board and not a cheap Arduino Nano or a MakeyMakey? The Invention Board is using a Teensy LC at its core which has built in capacitive touch, something the Nano or MakeyMakey does not. This means that you can just 'touch' a point and activate the board. If we used the Nano or MakeyMakey we'd have not only touch a point but also have our body touching a 'ground' connection. This isn't very elegant and also removes the ability to activate a touch point THROUGH vinyl or paper.

Step 3: Layout Your Poster Board

Decide how may 'touch points' you want on your poster board. We recommend between 4-6, otherwise you'll have to use really small pictures.

Using a pencil, measure out and mark where your graphics/ 'touch points' will be.

For good measure, cut some pieces of paper out to represent you putting pictures onto the poster board. Are they too small for your use case?

Using a ruler and pencil, make these same marks at around halfway and 3/4ths of the way up your poster board. This will help us keep our tape lines straight.

We used some self sticking Velcro to attach our LEGO base plate to the Poster Board, double sided tape would work fine as well.

Run tape from the various pins on the Invention Board down, over, and across to where you marked out your 'touch point' ends. The Maker Tape does right angle folds quite well, but if you want to cut it you can! Maker Tape is conductive on top and bottom so as long as you overlap two pieces you'll have a solid connection.

That being said, don't overlap individual lines that shouldn't be overlapping. You'll most likely want to use pins 15, 16, 17, 18, 19, 22, and 23 for this as they're all in a row. (Pins 3 and 4 are can also be used as 'touch points' if you want to have 9 inputs. The other pins on the Invention Board do not support capacitive touch.)

Step 4: Making Larger Touch Point Areas

If you wanted to you could have students just touch the tape lines and activate the sound effects. If you increase the sensitivity in the code you can add the ability to activate the 'touch points' through paper or stickers.

To help increase the surface area we made some overlapping tape shapes with our Maker Tape. All of our shapes worked well for our example project, but ideally you'd want to have tape under most of your picture.

Aluminum duct work tape is also very conductive, but only on the top side. You could put a piece of that at the end of your tap line, just make sure the Maker Tape is extended onto the TOP of the aluminum tape. (Make Tape is conductive on top and bottom. As lone as one piece of Maker Tape is overlapping another you'll have a solid electrical connection.)

The same can also be said about using conductive paint, such as Bare Conductive Paint. This would also create a large area to use as a 'touch point'. However in this situation it's probably far easier to just make a shape with conductive tape.

Step 5: Modifying the Code

Click this link to download our code, resources, and test sound files.

*** If the above link ever stops working go to our GitHub repo. We'll also ways the latest code and resource files there. ***

Overall you shouldn't have to change anything in it. The code is pretty simple. Touch a Touch Point and it plays an assigned numbered audio file.

Two settings you can and may want to change are:

1) Length of wait time between inputs.

In lines 23 - 31 you can change how much time each pin waits before accepting a new input. For instance if you want to be able to very quickly tap a Touch Point over and over and over again and have the sound file start up again every time you press it, change the length of time to 0.5 seconds.

For the rest of us just leave this setting in the 3-5 second range (or change each one individually to match the sound file length). This way people can't super tap your sound effects, but can easily activate a new Touch Point if they get bored with a long sound effect.

2) Sensitivity of the Capacitive Touch

On line 53 you can change this number to increase or decrease the capacitive touch feature. If you raise the number the sensitivity DECREASES, if you lower the number the sensitive INCREASES. Increased sensitivity means you can (probably) activate a touch point from a couple of inches away.

We keep ours at a sensitivity of 2,000. This means that people have to make physical contact with the paint on the wall and don't randomly activate it when walking by. Even at that low of a sensitivity we can still activate the Touch Points through piece of paper or piece of vinyl.

As a note to teachers of small children. Children have a much lower mass than adults do and it may be more difficult for them to trigger the 'touch points'. Changing the sensitivity will fix that.

Step 6: Upload the Code

Download the free Arduino software if you don't already have it.

Since we're using a Teensy LC inside the Invention Board you'll also need to download some additional resource files for that board. You can grab those for free off the PJRC website. (Mac OS 10.15 users must download a modified version of the full Arduino IDE from the PJRC website that has the built in resource files. The only downside to this is that it's a large file.)

Choose the Teensy LC as your Arduino of choice in the software and upload. (Mac OS 10.15 users will also have to choose the port that the Teensy LC is located at.)

Step 7: Loading Files Onto the SD Card

We've set things up so that certain pins are connected to certain folders. Change the file in that folder whenever you want a new sound effect. For instance Pin 15 is assigned to Folder 01, Pin 16 to Folder 02, Pin 17 to Folder 03, and so on. (If you ever forget, this is all laid out in the code.)

Windows Users:

Format the micro SD card in FAT. Create folders number 01-09 on the card. Drop the mp3 or wave files into each of those folders. Put the micro SD card into the mp3 module.

Mac OS User:

Open up Disc Utility and format the micro SD card as (MS DOS) FAT. Create folders on the card numbered 01-09. Drop your mp3 or wave files into those folder.

Now for some reason Mac OS create small invisible files that mess up the mp3 module so we created a work around. Download this script we wrote and stick it onto the SD card. Highlight all the folder (with the music files in there) and drag them into the script icon. This will remove the invisible files. You'll have to do this every time you change the sound files, which is why it's probably helpful to keep the script on the SD card.

Step 8: Testing Things Out

Stick the micro SD card into the mp3 module, plug in your speaker, and plug in your Invention Board.

STOP! Before you touch anything wait until the little LED on the Invention Board turns on. The code has a five second capacitive touch 'calibration' that takes place every time it powers up. Once the LED is on you're good to go.

No Sound

Is your speaker plugged in and the volume turned up? This is a mistake we've made before.

Double check your SD card is in. (And you did load up sound files, right?)

Check your connections from the MP3 board to the Invention Board. When you touch a touch point the little LED on the MP3 player module will start flashing, indicating that it's playing a sound file. If it's not flashing that means it's not getting instructions from the Invention Board.

Try running your fingers along the various pins on the Invention Board. Calibration may have failed.

You can only use .mp3 and .wav file types, others will not play.

Are you a child or a smaller person? Your body might not have enough mass to activate a Touch Point. Increase the sensitivity for better results.

Too Much Sound

If sound files are constantly playing, change the sensitivity and the time delays.

Wrong Files Playing (Especially in Mac OS)

You didn't use the script to clean up the invisible files.

Are your tape lines connected to the right pins?

Did you use numbered folders?

Try changing the file name of the files in the folders to numbers.

Code Not Uploading

Make sure you downloaded the Teensy plugin for the Arduino IDE.

Make sure Teensy LC is selected.

Sigh... make sure your Arduino is plugged into your computer.

Step 9: Lesson Plans

Download our Example Lesson Plans here.

To quote our Curriculum Writer Andy when talking about this activity:

"Although simple enough to approach this build AND the electronics/programming concepts which drive it with students, the invention board is even easier to assemble solely by the classroom educator. It can be affixed to nearly any surface in a classroom setting from tables to walls. When completed, an educator may load individual audio files that play when each separate touch pad is triggered. This can be useful in a variety of ways but primarily as a fun, classroom self-quiz station. Weave it into your classroom stations rotation…use it to motivate lame but still effective drill-and-kill practice sessions."

The problem with this project is due to the modular nature of it as an educator you'll have to find the RIGHT way to use it in your classroom. What works for one classroom and grade probably won't work right for someone else.

Our lesson plans provide some simple example activities for a couple of common situations in non-science classrooms:

1) ESL Classroom

This is the project we have represented in the pictures above. Students match the English (or Spanish) cards with the picture and voice clues.

One aspect that we highly recommend you implement is having students create the sound files for the project. Most modern computers and laptops have built in microphones. We used the built in microphone on our iMac with Quicktime Player (on every Mac) to record the audio in our example.

2) Math Classroom

Using a sound board to help students memorize multiplication tables is a very simple implementation that can easily be changed by the teacher each week. In our example plan we lay out a situation where a teacher loads spoken numbers into the system and then has students write out multiplication solutions using those digits.

Story problems are also a very easy implementation of this project using both numbers and pictures.

3) Language Arts Classroom

For younger students a Story Board can be used to have students put stories into chronological order. This is another situation where students can help out by recording stories that they create.

Other ideas would be bern conjugation or just simple vocabulary practice.

Step 10: Final Thoughts

This scaled down version has heaps of applications for classrooms or home learning, especially since this project can be made for under $100 and is endlessly changeable. It's engaging, high interest, and allows for student led activities and creation. We only wish that we'd had this back in our own classrooms.

What kind of fun classroom activities would you put together with this kind of project?

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