For our Makerspace's January build night, we worked with MakeyMakey kits. These kits are particularly well suited for working with the software program Scratch. Scratch allows you to link the circuits you make with your MakeyMakey with sounds, images, text and actions on the screen.
In my case, I recently took a trip to the Grand Canyon, where I had learned about the most common insectivorous bats that live there. I have a bat detector, and since it is a tool that works best when you know what frequencies each species of bat makes, I wanted a related tool that would help reinforce my ear for detecting the bats and their frequencies, while relating it back to the pictures of the specific bat. Kind of a museum exhibit for my own knowledge.
The project took me about 3 hours, but that's because it took a while to find all the .wav files I needed and to cut out the bats themselves. The Scratch programming is quite simple and should be useable even for kids.
Step 1: Gather Your Materials
For this project, you will spend time programming the MakeyMakey, but you will also need to put together the physical set up of the mobile. Think ahead to what flying creatures you want to learn about, and identify a food source that works fairly well for all of them. Track down photos online of the animals and .wav files of each, and save those to your computer.
Here are the different items you will need:
- Computer, printer, internet access & paper
- .wav files of each animal (save these with useful names)
- images of each animal (save these with useful names)
- aluminum foil
- glue stick
- MakeyMakey kit
- Scratch account (you can make this without a scratch account, but the account means you can save your program).
(I put a photograph here of my bat detector, but it is not necessary for this project. You can however find out how to build a bat detector online, and I recommend doing so if you like soldering and finding bats).
Step 2: Print Your Photos
In my case, I wanted three different bat species (the Mexican Free-Tailed Bat, the Pallid Bat and the Western Pipistrelle Bat), and their common food source: a moth. I pulled each file into word, and made them a size that would be useful for my bat-mobile. I duplicated each and reversed it by 180 degrees, to create the flip side that would be pasted on the back of each image. Print each image and its reverse image, and cut them out.
Step 3: Find .wav Files for Each of Your Animals and Edit Them With Scratch.
By doing a google search with the name of your animal and .wav in the search box, you can find a wide selection of animal sounds. In my case, I wanted frequency recordings of bat sonar, which are not detectable to the human ear, but which luckily were still accessible. Once you save these files to your computer, upload them to Scratch. In the Scratch editor, click the "Sounds" tab and you can use the buttons there after you upload your sound to edit it. It's useful to take out any silence at the start and end of your sound so that the response is more immediate when you complete the circuit. Save your edits, so that you can easily put in your sounds when you make your Scratch program. Scratch allows a step that plays the sound once, or that plays it repeatedly until you open the circuit. You can pick which one works for you.
Step 4: Use Scratch to Set Up the MakeyMakey Actions.
Playing with Scratch is the best way to become comfortable with how it works. Setting up the different icons to lead to different actions will show you how to use it even before you connect your MakeyMakey. In my case, I set up a couple different routines, which you can see in my program here. First of all, I created statements that allowed for the actions: "WHEN <certain key> is pressed, PLAY SOUND <certain bat sound> until done, SWITCH BACKGROUND to <picture of bat> BACKGROUND NAME of <name of bat>". Doing it this way with well-named files allows you to exactly see what will happen with each of these little routines.
My second routine was for the introduction and initial background screen, and was even simpler: "WHEN <green flag> clicked, SWITCH BACKDROP TO <picture of location where these bats live>, BACKDROP NAME (which shows the intro to the program in text)".
I recommend doing one full step before building all the rest. You'll want to test it with your MakeyMakey first in the next step.
Step 5: Connect Your MakeyMakey.
The MakeyMakey kit contains a USB cable, the MakeyMakey circuit board, and several alligator clips and other wires for making your connections. Straight out of the box, you can hook up an alligator clip to any of the four different arrow holes, and then one to the ground, which is the silver bar with holes in it across the bottom. Plug in the USB cable between your board and your computer, and Scratch should work with your MakeyMakey without any additional setup. Now you can hold the end of the alligator clip that leads to the arrow key and hold the end of the alligator clip that touches the silver ground, and make the circuit (yes, YOU are conductive!). Do this with your first routine, clip in to the specific arrow key you used in that routine and check that completing the circuit with your hands like above gives you desired action. You may have to play around a bit to get it to do exactly what you want.
Step 6: Use the Glue Stick to Attach Your Mirrored Animal Images and Give Them a Good Simple Contact Space.
Since you have the cut out mirror images of each of your animals and the food source, glue them back to back to make the double-sided animals.
The connections made by the MakeyMakey depend on conductive material. The kit instructions suggest that you could just touch the alligator clip metal ends with your hands, or you can deposit a lot of graphite on the surface to be touched with a pencil (which I found to be unreliable). To make it extra easy for all of the people using your kit, give them a bigger surface to touch with aluminum foil, which is conductive.
In my case, I cut out hearts for each animal and the moth. You can cut out whatever shape you want, and affix it to each animal on both sides with the glue stick, close enough to an edge that the alligator clip can be attached and make good contact with the aluminum foil.
Step 7: Test Your Scratch Routine With the Paper Animal Images.
Now your first circuit is ready to go. You should have the MakeyMakey connected to your computer, your Scratch program open and live, an alligator clip between the specific arrow key and a bat's silver heart, and a second alligator clip between the silver MakeyMakey board ground and the moth's silver heart.
Do this by now touching a bat's silver heart with one hand, and the moth's silver heart it wants to eat with your other hand. Doing so should complete the circuit and run your routine. Connecting the bat to the moth plays its feeding sonar frequency and displays the bat's name and photo for identifying the bat through its image and sound. You now have a learning device for IDing this bat when hearing its sonar frequency!
Step 8: Complete Your Other Routines in Scratch.
Now that you have a working routine, copy it inside your Scratch program by dragging the Scratch icons onto your Scratch workspace again and updating the file references so that you have one routine for each animal. You can also create the startup screen by creating the routine I show at the bottom which displays the environment background.
Step 9: Hang Your Educational Mobile From an Appropriate Spot, and Teach Your Friends!
I used this project to show our workshop attendees how the MakeyMakey works, so I hung it from our welding equipment where they could see it as they came in. But you can hang it using something more attractive - put the MakeyMakey at the top, and use the alligator clips natural length as the way to dangle the bats. Keep your computer close by so you can turn up the speakers as needed!