Our seniors wanted to leave a mark, so after their initial application to paint the outside wall of the gym was turned down, they went with a mural on the inside–in our Makerspace.
For this project, we wanted to create a mural on the basementnasium wall. First, we measured the wall and went to Home Depot to get enough paint, paint brushes, drop cloths, and tape. Then, after cleaning the wall with a damp cloth, we covered the wall with tape in a triangular pattern similar to one we found online. After that, we used pencil to mark each triangle with a letter corresponding to one of the six colors that we bought. It took us the majority of the project to paint 3-4 coats on each triangle, and on the last day we pulled it the tape and touched up any mistakes with white paint.
Throughout this project, we found out that some people know how to paint, some people learned, and others didn’t learn. BUT IT WAS SO MUCH FUN!
-Team: Elliott, Abby, John, Zoe, Mary, Annemarie, and Josiah
Longboard built during the interim.
Finishing came afterwards.
For my makerspace project I made a longboard. What went well with the board was the wheels and trucks, it was a simple hole in the wood and screwing the trucks almost no measuring on my part. What didn’t go so well was the measuring and cutting of the board, it took me a full day to get all the measurements exact and even then they didn’t come out so good. What I would do next time is get a cnc machine so it does the measuring and gets the cuts exact every time. We could mass produce longboards with ease. If i did it again without a cnc machine i would get the measurements beforehand and then it would make measuring a lot easier.
After building our vegetable boxes, I had one of the students use some of the wood scraps to make some small stools. They make it easier for us to sit cross-legged on the floor. This last interim, as a small side project, another student chose to upholster them:
During the interim, I worked on upholstering small wooden stools that Dr. Urbano had made. I worked in the basmentnasium and only used the materials available there. I used thin layers of foam from an old couch to pad the wooden seat; if the foam was too thin then I used two layers. I covered the foam and the seats’ edges with fabric Dr. Urbano brought: a burlap rice bag and old curtains. I attached the fabric to the bottom of the wooden seat with a staple gun; I attached it tight enough to keep the foam in place.
Inspired by a video of a temporary bridge built out in the woods for mountain biking, my students wanted to try building a “natural” bridge with no fasteners–no screws, no nails–over a small ravine that feeds into our creek.
The base of the bridge.
We found a couple large fallen logs to cut into two 10 foot lengths for the basic structural support for the bridge. These were dug into the ground to anchor them on either side of the ravine. We then chopped a couple more logs into 2 foot sections to go across the structural logs. The dense mud from the banks of the creek was then packed onto the top to hold it all together.
Packing mud.
In the end, the bridge turned out to be pretty solid, and definitely usable.
My crew from the Gaga Ball pit decided to make a trail through the woods and across the creek. So they built two short (12 ft long) bridges to cross the creek itself, and a third, “natural” log bridge to cross a small ravine that runs into the creek and cuts across the trail.
The short bridges were made of overlapping 2×4’s for structure (held together by 2.75 inch structural screws), with 24 inch long, 1×6 planks across the top.
Short bridge under construction.
The short bridges needed to be small and light enough to be moved when the creek rises, like it did today. I’ll attest that they can be moved, but not easily. They’re pretty heavy: it took a team of three or four middle schoolers to get it down to the creek, and it was hard going trying to drag it over to the side by myself this afternoon. Note to self: next time make sure the structural cross pieces are not at the very end of the bridge.
This interim focuses on our global community. As a result, one of our Chinese students gave a lesson on a traditional dance. I think I made a good start at learning the twirls, but we did not have time to get to the jumps.
LED light circuits on a breadboard controlled to Raspberry Pi via a cobbler (connected to a ribbon of wires).
Although it took us a day to figure out how to get the Raspberry Pi to work–a faulty SD card turned out to be a major delay–we still had most of a week of the Creativity Interim for students to get some projects done.
That is, until it started to snow. We lost more two days.
Still, we had a small cadre of determined students, one of whom (N.D.) decided that she wanted to make the Pi play sounds to go with the blinking LED lights.
To do this she needed to:
Learn how to use the LINIX command line to connect to the Pi and execute programs.
Learn how to write programs in Python to operate the Pi’s GPIO (input/output) pins.
Learn how to make circuits on a breadboard connected to the Pi.
A Quick and Incomplete Introduction to the Command Line: Basic Navigation
We started by using the Terminal program on my Mac to learn basic navigation.
To see a list of what’s in a folder use ls:
> ls
For more details on the items in the folder, use the -l option:
> ls -l
To see all the options available for the ls command you can lookup the manual using man:
> man ls
To create a new directory (e.g. Pi) use mkdir:
> mkdir Pi
To change directories (say to go into the Pi directory) use cd:
> cd Pi
Connecting to the Pi
I detail how to connect to a Pi that’s plugged into the wall via the local network here, but to summarize:
Use ifconfig to find the local IP address (under eth1).
> ifconfig
Use nmap to identify where the Pi is on the network. E.g.:
> sudo nmap -sP 191.163.3.0/24
Finally, connect to the Pi using the secure shell program ssh:
> ssh pi@191.163.3.214
(the default password is “raspberry”)
Wiring an LED Light Circuit
A circuit that connects the #17 GPIO pin to a red LED light then to a resistor before going back into the ground (GND).
We created an initial circuit going from the #17 General Purpose Input/Output (GPIO) pin to a red LED then through a resistor then back into one of the ground pins of the Pi. We’ll turn the current going through GPIO #17 on and off via our program on the Pi. The resistor is needed to reduce the amount of current flowing through the LED, otherwise it would likely get blown out. The circuit is shown in the picture where I’ve taken the wire ribbon out for the sake of visibility.
Wiring on a breadboard is quite simple if you remember a few rules.
First, the columns of holes on the sides are connected vertically, so the right end of the yellow wire (in the + column) is connected to the resistor.
Secondly, the holes in the middle are connected horizontally, but not across the gap in the middle. That’s why the GPIO pin #17 is connected to the lower end of the black wire, and the left end of the resistor is connected to the ground (GND) pin. The LED light reaches across the two gap to connect the two rows with the upper end of the black wire and the left end of the yellow wire. Without something to bridge the gap, the circuit would not be complete.
The resistor has a resistance of 420 Ohms. You can tell by the color bands. In the sequence–yellow, red, brown–the first two bars represent numbers (yellow=4; red=2) and the third number represents a multiplier (in this case brown represents 10x).
Light: Programming the Pi in Python
Once you ssh to the Pi you can start programming. We used the command line text editor Nano. A simple text editor is all you need to write simple Python programs. We’ll create a program called flash.py (Note: it’s important to include the .py at the end of the file’s name, otherwise it becomes hard to figure out what type of file something is, and the extension also clues Nano in to allow it to color-code the keywords used in Python, making it a lot easier to write code.
pi> nano flash.py
You can then type in your program. The basic code for making a single light flash on and off ten times (see here) is:
flash.py
#!/usr/bin/env python
from time import sleep
import RPi.GPIO as GPIO
cpr = 17 ## The GPIO Pin output number
GPIO.setmode(GPIO.BCM) ## Use board pin numbering
GPIO.setup(cpr, GPIO.OUT) ## Setup GPIO Pin 7 to OUT
for i in range(10):
GPIO.output(cpr, True)
sleep(0.5)
GPIO.output(cpr, False)
sleep(0.5)
GPIO.cleanup()
This requires wiring a circuit to the GPIO pin #17. The circuit has a LED and a resistor in series, and circles back to the Pi via a grounding pin.
Run the program flash.py using:
pi> sudo python flash.py
Finally, let’s tell the program how many times to flash the light. We could create a variable in the Python code with a number, but it’s more flexible to set Python to take the number from the command line as a command line argument. Any words you put after the python in the command to run your program are automatically stored in an array called sys.argv if you import the sys module into your program. So we rewrite our flash.py program as:
flash2.py
#!/usr/bin/env python
from time import sleep
import RPi.GPIO as GPIO
import sys
cpr = 17 ## The GPIO Pin output number
GPIO.setmode(GPIO.BCM) ## Use board pin numbering
GPIO.setup(cpr, GPIO.OUT) ## Setup GPIO Pin 7 to OUT
for i in range(int(sys.argv[1])):
GPIO.output(cpr, True)
sleep(0.5)
GPIO.output(cpr, False)
sleep(0.5)
GPIO.cleanup()
So to flash the light 8 times use:
pi> sudo python flash2.py 8
Note that in your Python code you use int(sys.argv[1]) to get the number of times to flash:
sys.argv[1] refers to the first word on the command line after the name of the python file. sys.argv[0] would give you the name of the python file itself (flash.py in this case).
the int function converts strings (letters and words) into numbers that Python can understand. When Python reads in the “8” from the command line it treats it like the character “8” rather than the number 8. You need to tell Python that “8” is a number.
Sound: Using SOX
You can do a lot with sound–record, play files, synthesize notes–on the Pi using the command line program SOX. Install SOS (and mplayer and ffmpeg which are necessary as well) using:
pi> sudo apt-get install sox mplayer ffmpeg
Installation may take a while, but when it’s done, if you plug in speakers or headphones–the Pi has no onboard speakers–you can test by synthesizing an E4 note, which has a frequency of 329.63 Hz (via Physics of Music Notes), that lasts for half a second using:
pi> play -n synth .5 sin 329.63
Now play is a command line program that’s part of sox, so to use it in your Python program you have to tell Python to import the module that lets Python talk to the command line: it’s called os. Then you make a Python program to play the note using os.system like so:
test_sound.py
import os
os.system('play -n synth .5 sin 329.63')
And run the program with:
pi> sudo python test_sound.py
Combining light and sound
Now we bring the light and sound together a the Python program:
flash-note.py
#!/usr/bin/env python
from time import sleep
import RPi.GPIO as GPIO
import sys
import os
cpr = 17 ## The GPIO Pin output number
GPIO.setmode(GPIO.BCM) ## Use board pin numbering
GPIO.setup(cpr, GPIO.OUT) ## Setup GPIO Pin 7 to OUT
for i in range(int(sys.argv[1])):
GPIO.output(cpr, True)
os.system('play -n synth .5 sin 329.63')
GPIO.output(cpr, False)
sleep(0.5)
GPIO.cleanup()
which you run (repeating the note and light 5 times) with:
pi> sudo python flash-note.py 5
Notice that we’ve replaced the middle sleep(0.5) line with the call to play the note because we don’t need the delay since the note plays for 0.5 seconds.
Playing a Tune
N.D. wires LED’s and resistors on a breadboard connected to a Raspberry Pi.
The student, N.D., spent some time working through this programming and adding wiring to the Pi breadboard in order to play the first few notes of Mary Had A Little Lamb. By the time we ran out of time, and she had to do her presentation to the rest of the upper-school, she’d come up with this:
red-light-flash.py
#!/usr/bin/env python
from time import sleep
import os
import sys
import RPi.GPIO as GPIO
os.system('play -n synth 2 sin 543.21')
cpy = 22
cpr = 17
cpw = 23
GPIO.setmode(GPIO.BCM) ## Use board pin numbering
GPIO.setup(cpy, GPIO.OUT) ## Setup GPIO Pin 0 to OUT
GPIO.setup(cpr, GPIO.OUT)
GPIO.setup(cpw, GPIO.OUT)
for i in range(int(sys.argv[1])):
GPIO.output(cpy, True)
GPIO.output(cpr, False)
GPIO.output(cpw, False)
os.system('play -n synth 1 sin 578.00')
GPIO.output(cpy, False)
GPIO.output(cpr, True)
GPIO.output(cpw, False)
os.system('play -n synth 2 sin 440.00')
GPIO.output(cpy, False)
GPIO.output(cpr, False)
GPIO.output(cpw, True)
os.system('play -n synth 1 sin 400.00')
GPIO.cleanup()
which is run (5 times) using:
pi> sudo python red-light-flash.py 5
Creating User-Defined Functions
(As a note to N.D., because we ran out of time before we could get to it.)
You’ll notice it takes four lines to turn a light on, turn the other lights off, and play the note. You’ll also note that you have to repeat the exact same code every time you want to play a specific note and it becomes a pain having to repeat all this every time, especially if you want to play something with more notes. This is the ideal time to define a function to do all the repetitive stuff.
So we’ll create a separate function for each note. Mary has a little lamb uses the notes E4, D4, and C4. So we get their frequencies from Physics of Music Notes and create the functions:
