Hack the Teacher - A lesson in physical computing using a Raspberry Pi Zero Christmas Jumper

Just before Christmas I had some fun with a Christmas Jumper and Physical computing based around the (then) new Raspberry Pi Zero. Here is the rather belated write up of the lesson.

I was not quick enough to get hold of a Magpi issue 40 when they were first in the shops so I subscribed and waited for it to be delivered to my door. Initially I didn't really know why I wanted the attached free Raspberry pi Zero, I just knew I wanted one.

The Jumper

However when it arrived inspiration arrived with it and I decided I needed to make a Christmas jumper and that it would be a really good tool to get some of my students interested in programming. I came up with a simple plan of a Christmas tree with some lights and set about creating the base for the project.

This was all going well apart from two factors; I now only had a weekend to complete the project to be able to use the jumper in lessons (before the end of term), and my inability to sew.

Not one to be daunted I found some felt and cut out the basic shapes then had a crash course from my wife on how to attache them using needle and thread. So I eventually (after a late night sewing) managed to attache the tree using a simple running stitch in the centre of the tree and then added blanket stitch around the edge to secure it in place (and add decoration). From a distance the effect was relatively respectable. (if you look closely you can see that the quality of my blanket stitch improves as it goes around)

The second evening I spent setting up the electronics. I played with a couple of different configurations but in the end decided on individually programmable LEDs. Each LED is connected to a separate pin on the Pi Zero and to Ground. This left maximum flexibility in what could be done with the lights.

I had initially thought about hiding all the connections inside the jumper but as I was putting it all together I quite liked the idea of it all being visible. To this end all of the wiring was attached to the front of the jumper and the Pi Zero itself was sewn onto the jumper. I also used a portable USB power supply to allow me to walk around without being tethered to a plug socket.

After getting it all wired up I connected the PiZero up to a monitor and set about creating a test program that would show the lights on the tree working. It could also be used as a starting point for the students to modify the existing code to create their own sequences. To make it a little easier I set up a few functions that set groups of light as on or off and the made a short sequence using the functions. I set this up to start on boot so I could just connect the power and the light sequence would start.

The video shows one of the LEDs had failed but this proved to be a loose wire that was hastily soldered up and everything was up and running.

The Lesson

The idea for a lesson using the jumper was inspired by last years code.org hour of code which had students programming a sequence of lights for Christmas trees outside the Whitehouse.

The plan was to explain how the GPIO library is used to turn the lights on and off and then let the students view the code for the existing sequence before coming up with their own code to control the jumpers LEDs.

Preparation

To allow students access to the PiZero I needed to connect it up to the school network. The plan was to do this over wireless with a USB wireless network adapter. (in reality I had problems getting onto the school WiFi network so I took off the jumper and used a wired adapter instead) The students could then login to the PiZero using SSH and use nano to create their programs.

The students downloaded putty to their workstations in order to do this.

Introduction
Demonstration of the jumper working

Explanation of GPIO Library commands to control the LEDs (including the functions I created earlier)

Main Activity
Students to design an algorithm for the light sequence

Students to use python and the GPIO library to program the sequence - this was done by logging in over SSH using putty and copying the basic file (including the functions and GPIO setup) giving it their own name.

Students test the code on the jumper - this required a bit of co-ordination to ensure we only ran one script at a time.

Extension
Able students create their own functions that they can reuse in their sequence.


Plenary
Demonstration of some of the best (aesthetically) sequences

Discussion about code efficiency and creation of functions to avoid duplication of code


Review

The lesson went well with a good deal of enthusiasm generated by the idea of 'hacking the teacher' the students were initially very overly excited by downloading putty and being able to log in remotely to the Raspberry Pi on my jumper.

The students were fairly quick to be able to get a short piece of code working (mostly just a single flashing LED) and then move on to experimenting with using the functions I had built.

At this stage there was a good deal of discussion about what they could do that would be amusing (fortunately I had thought of this at the design stage and I think I managed to avoid any embarrassing light combinations of a phallic nature, or at least they didn't find any during the lesson). Once they had discovered they could not create anything rude they settled for pretty and started to compete on who could create the best sequence.

There was lots of experimentation of how fast they could get lights to flash or change and with what sort of changes looked good. Some of this was a little held up by the fact that there was only one jumper so students occasionally had to wait for someone else to test their code before they could run theirs. It might have been good to have some breadboard prototypes for testing to reduce some of the waiting but i feel that that may have spoiled the interest provided by making the code run on my jumper. This would have been even better if we could have got on over wireless and I could have been walking around the room whilst they were testing their code on me but this was a small niggle.

Overall the lesson was a great success with students engaged in creating code and experimenting to see what they could do as they learnt more about how the Library worked. There were some great creative responses and some good use of functions with parameters for time that could be reused at different points in the code.

If i did this again with another class I would probably use the GPIO Zero library to reduce the code required to get things working but with students staring by using my example code they had a reasonable start anyway.


The rest of the day as I walked around school I did spend alot of time assuring students (and some staff) that "No it's not a bomb" (it was just after Ahmed's clock incident) and "No I won't catch fire". However I did get several question about how it was made and could they make one too, so hopefully some more students aware of the possibilities of computing.

BETT 2016 - Raspberry Pi physical computing workshop

Last year I was intending to run a workshop for Raspberry Pi at BETT but was recovering from an appendectomy instead. This year tempting fate I volunteered again and fortunately avoided any surgery in the run up to the show.

I had been working with ,my son Toby who had created his own robot using the CamJam EduKit 3 and I had used GPIO Zero to help to reduce the level of typing required to get his creation working. As I intended to talk about Physical computing Toby came along too with his robot. to show what could be done with a few simple lines of code.

He was very pleased to be able to show off his creation and say a little about how he had made it. he was also very excited to have his own badge with his newly created job title.

We then got hands on and had the attendees making their own simple circuits and writing the code to make things happen in the real world. Having some hands on time was a really powerful tool to demonstrate how quickly results could be seen using simple components and GPIO Zero. I did promise at the show that I would add the presentation here with the information links so here it is on Prezi - Lets get physical -  an introduction to Physical computing with GPIO Zero.


The show was challenging environment to deliver training in with all of the competing noise and activities occurring around the stand. It was an interesting cross between market trader and teacher. Attracting people into the stand and then guiding them through creating a circuit and controlling it with code It was also a challenge with people arriving to the stand (attracted by what was happening) part way through the session and wanting to join in.

The sessions both ran slightly different to the plan (and  to each other) but I think we were able share the power of being able to make things happen in the physical world.  I think especially with the late arrivals it was a great demonstration of how results can be achieved really quickly using GPIO Zero due to the less onerous volume of code required.

If i was going to do this again i would probably take some pre-prepared  kits with the components for the circuits or even use a HAT to simplify the process. I would also think about printing some copies of the code / circuit diagrams to make it easier to manage with late arrivals and swapping the screen around from basic to advanced tasks. Having both on a laminated card (or just a bit of paper would do) would have made it easier for those who arrived late to have a play with the basic example without me having to switch the screen back and forward.

GPIO Zero - making coding less language intensive.

In a previous post Getting Physical with Python I wrote about the difficulty some of the younger children in my computing group had with the volume of typing required to get started with physical computing. They did not struggle with understanding but it took too much time and help to enter the volume of text required. This took away some of the excitement and slowed things down.

At the time I thought to speed this up it would be good to write a python library to reduce the amount of text needed to get things to happen. Unfortunately I had lots of other things to do and this never went anywhere. However someone else also thought it would be good to make it easy to get started with physical computing and was able to do something about it.

That person was Ben Nuttall of the Raspberry Pi Foundation. Along with Martin O'Hanlon and Dave Jones he has created GPIO Zero. You can read his account of how it happened on his blog.

This python library can be used to very simply control components using the GPIO pins. The initial function set is based around the popular CamJam EduKits  (Kit 1- Starter, Kit 2 - Sensors) and makes a great starting point for physical computing using python.

A simple light and button combination can be controlled with the below example:

from gpiozero import LED, Button led = LED(15) button = Button(14) button.when_pressed = led.on button.when_released = led.off

instead of something like this:

import os 
import time  
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM) 
GPIO.setwarnings(False) 


GPIO.setup(14, GPIO.IN)
GPIO.setup(15, GPIO.OUT) 

while True: 
        if GPIO.input(14) == False: 
              GPIO.output(15, HIGH)   
        else: 
               GPIO.output(15, LOW)  

 time.sleep(0.5) 

The reduction in volume of code and setup required is brilliant. GPIO Zero is an amazing tool for education. This is especially true where the volume of text entry is a barrier (either with younger or SEN children).

The tool allows the focus to be on the programming concepts and not on the entry of text. When i worked with my HomeEd computing group there was a difficulty fro a number of the students (aged between 5 and 15) in using the GPIO library as there was a lot of code to enter. They were generally happy with what they were trying to achieve but found that it took a long time to enter the lines of code required just to light up the LEDs.

This meant that in the one hour session that is what we achieved, lighting up the LEDs. Whilst this was a success and the children were happy with getting there it would have been much better to spend more of the time in the session exploring what could be done rather than entering lots of text.

GPIO Zero takes away some of the burden allowing children to focus on what they are trying to achieve rather than on copying out lots of lines of code (especially the set up parts that are conceptually more difficult to grasp and result in questions about what is BCM etc).

I have found that where I have used this it has meant I can more on more quickly and cover more of the computational thinking ideas where previously there would have been more time waiting for the students to catch up with the typing required. It also works well to satiate the desire for instant gratification that appears to be fairly common among my pupils. They only have to spend a short time entering code before they can see a result.

It is also much easier in a classroom to debug the code they have written if there are errors. The reduced volume of code makes for less searching to find the capitol that should't be there. This make students more able to do it themselves or makes it quicker for me when they can't see what is wrong. The reduction in time taken here give me the opportunity to get to more pupils and help them to progress.



I have also used this at home with my son (8) whilst he has been creating a robot using the CamJam EduKit 3 - Robots. This was really powerful because it allowed him to achieve results in short pockets of time before he lost focus and wanted to move on. He used the provided worksheets to set up the robot and connect the components and I translated the code parts into GPIO Zero for him to get the robot working.

So in summary the feedback is - Thanks Ben this is an awesome tool to help me teach computing.

If you are interested in using GPIO Zero there is a great getting started guide on the Raspberry Pi website in the resources 'Learn' Section.

More information can be found on pythonhosted.org or on GitHub. There is also a Google Doc with information and a place to add comments / requests.