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Friday, 12 April 2013

Deploying Raspberry Pis in a Classroom - Problems & Solutions

Since January I have been working hard to try and bring computing via Raspberry Pis into my secondary school specifically for key stage 3 students. I chose Raspberry Pi to do this for a number of reasons:
  1. Using Pis would bypass any issues with the school network and workstation configurations that would hinder computer program development. 
  2. Using a different device would broaden students understanding of what a computer is (hardware) and what you can do to it.
  3. We would only require a class set of Pis and could use many SD cards for each group.
I was very fortunate to meet Alex Bradbury (@asbradbury) at PyConUK in September and he put me in touch with the foundation to develop a scheme of work for KS3 using Raspberry Pis. The focus of which was to teach programming concepts through using the Pi as a synthesizer. Sam Aaron (@samaaron) programs music and fully understands the power of creativity in getting concepts across to children. He developed the Sonic Pi (@sonic_pi) a way to program the Raspberry Pi to make very cool electronic music. Together we spent December, January and February testing our theories, teaching ideas, and Sam's software on two classes of Year 8 students of different abilities.

Sonic Pi in action

Before I was able to do this I have had to overcome a number of issues with getting the equipment necessary. Simply buying a number of Raspberry Pis, say 30 for one each in a class or 15 for one between two (the option I decided upon) is not enough. There are the hidden costs:

Monitors and Adapters

Firstly, all of our classroom monitors are VGA. This is true of many schools across the country. A large proportion of our school computers are also RM Ones so the monitor is part of the unit and not separate. I did not see buying at least 15 HDMI monitors being feasible.

Many suggested using HDMI to VGA adapters. There are known issues with using cheap HDMI to VGA adapters that can blow the diodes on the Pi. Some people have had success with adapters, but on the whole it is a bit of an unknown. There is a recommended adapter from Farnell but as you can see, it costs almost as much as a pi, which when you times by 30 that you may need for one or two classroom sets becomes a huge cost.

As part of our KS5 BTEC course, we instruct students how to build their own computers, and luckily there were approximately 8 DVI monitors that I could use. I decided to make a plee to the Raspberry Pi community via twitter and the forums for any old DVI monitor they may be throwing out. Someone in Essex responded and I managed to end up with 12 DVI monitors. I then sourced 12 HDMI to DVI adapters that we used in class. They always worked and I had no problems with this solution (other than finding monitors)

SD Cards, Images and Backing Up Work

Again, there are some issues with SD cards and Raspberry Pi's not being completely compatible for whatever technical reason leading to corrupting data. Large sets of SD cards can also be expensive. I opted for ScanDisk 4GB SD cards, which Sam would take back to Cambridge at the end of each lesson to develop the software further. His biggest nightmare being that he would have to re-image 15 cards one at a time nearly every week, and after a few months the cards started to drop off till we ended up with 12 working ones.

For me to roll this scheme of work out across a whole year group, with at least two ICT classes taking place at the same time 6x30 SD cards. I'd also need a way to back up students work from the cards. Sam had designed the software so that it would automatically save the students work on worksheets, and I numbered the cards so that I could assign them to pairs of students, but the work students produced is still on those cards, it would be nice if it could have been exported to a text file students could use for assessment on a standard PC, and for the music to be exported as a wav or mp3 to go with it.

Alex Bradbury has solutions for the problem of imaging multiple cards (as can be seen from his Raspberry Jamboree talk) and also the second issue of being able to back up students work via a 'magic usb' memory stick.


One of the joys of teaching using Raspberry Pis is to see students being fascinated by the naked board itself and discovering what each part is. However it is not feasible to have the Pis in this form when setting up and packing away in a 50 minute lesson. I used the Pimoroni PiBow cases and found them to be very robust, they are also nicely labelled for the students and they can still see the board. The only problem students found was plugging in the power supply as the connector would slip and not plug in nicely.
Of course they do not come cheap, and they have to be assembled. I think by now I can assemble a pibow in my sleep with the number that I have done since the start of this project.

Micro USB Power Supplies, USB Keyboards and Mice

Easy enough to source these cheaply, but they are another expense. Again some of the classroom equipment was quite old, so some peripherals had PS2 connections, and as we were using separate monitors it seemed more appropriate to use separate keyboards and mice.

Earphones and Audio Splitting Cables

As this scheme of work involved music, splitting the audio output for students to work in pairs was another equipment issue. First it was suggested we use little speakers, however the thought of 15 different noises playing out all at once instructed by 13 years olds filled me with a terrible sense of dread. Instead I asked students to bring in their own earphones or headphones. At first this worked fine but by week 4 they started to forget. In future I will buy some cheap sets of earphones. We also procured some audio splitting cables cheaply through ebay.


My project did not involve plugging the Pis into the network for many reasons. The first being the complexity of the already locked down school network. I am fortunate in that like many of you I work in a school with a fantastic support staff, who work tirelessly keeping out of date equipment up and running for a large number of users. The last thing this team needs is me asking to add a complete unknown to the network. Yes it would have been nice to find a way to perhaps use sounds from the internet, or have students be able to save their work into their Google Apps Drive, but overall it was not necessary. Perhaps something for the future?

Trailing Ethernet cables and locating ports in the classroom could also have been difficult, with wifi solutions for the pi being an added cost, and something else to configure/potentially go wrong?

Classroom Space, Health & Safety

The problem with using completely separate equipment to that already existing in an ICT classroom is of course space. I had tables set up in the center of the class, with two students per table. I had to run extension cables from power sockets (another expense), which then had to be covered for health and safety, which is not ideal. I'd rather use the Monitor, keyboard, mouse, plug sockets, power cables, and network port already existing in a classroom (as long as it is not a classroom filled with RM Ones) Then all that would be needed would be a Raspberry Pi and an SD Card.


At the start of every lesson, I moved the tables, put extensions cables in and covered them, and then put all the equipment out onto the desks. I did this a few times on my own when I was lucky to have a free period before or a break. Most of the time I had a team of sixth formers who helped. Without their help it would have been a very difficult task. Another reason to try and use equipment already in place. Students at the start of the lesson plugged in all their equipment and 5 minutes before the end of the lesson shut down their pis, unplugged everything and I collected all the parts into separate boxes which I then locked into a cupboard. I'm not sure how well this will work when multiple classes need access to the equipment at the same time. Sixth formers have to do their own work on occasion!

Finally the Raspberry Pi itself

Out of a batch of 15, one did not work straight from the box. I blame Rob Bishop because he gave them to me. Just kidding. The failure rate was obviously very low as I had no problems after that.

Further Funding

I was lucky in that the Raspberry Pi Foundation invested some funding into this project to get it started so that Sam and I could produce a scheme of work that could be used by other teachers across the country for free. But now I want to roll it out across an entire year group I need funding to do so and the piggy bank is bare.

Schools are facing cuts left right and center. We have equipment that is incredibly out of date, and work in buildings that were not designed for 21st century classrooms. I have just applied for a small grant of £500 for which I had to submit quite a long proposal. There is no guarantee I will get this and so will have to wait for next years budget and hope that after paying for the necessary text books for KS4 and 5 that there is some money left over for KS3.

I have an extremely supportive SLT who see the value in which I have tried to do. I've even been visited during this project by a school governor with a maths and computing background who saw the enjoyment the students had programming the Pi. But the truth is there is currently no funding. Something the government should consider when changing the program of study for ICT/Computing!

It has been suggested that crowd funding classroom sets of Pis is a good way to get the funding needed. As spoken about by Paul Hallett (@phalt_) at the raspberry jamboree. However I feel that although this is a great suggestions, in a low income demographic such as Dagenham, it would be unfair to put that strain on families.


The Sonic Pi scheme of work is almost ready for teachers to try. Overall it has been a truly valuable experience and students enjoyed and achieved more than I expected them to. Yes deploying raspberry pis into school is somewhat difficult currently and there are issues that need to be addressed. I will still forge ahead with my plans though. If you are interested in my Pi story so far check out my talk at the Raspberry Jamboree:


  1. "It has been suggested that crowd funding classroom sets of Pis is a good way to get the funding needed.....However ..., in a low income demographic such as Dagenham, it would be unfair to put that strain on families.
    Miss Philbin - I suggest to you that you might not be thinking big enough. Given that you're on Google+ *and* someone else picked up and shared your story - you might consider an appeal there. I suspect that you could reach out far past your local demographic for a few pounds of support - if you can actually figure out a good way to receive it (PayPal, perhaps?).

  2. Hi Miss Philbin,

    Great to see a teacher using the pi for computer science - very important for kids to realise what the hardware is and what an operating system is.

    I agree with your comments on the monitor and other hardware costs and I myself have given up on using a monitor as too inconvenient. I have set mine up so that I connect via VNC to an existing PC on my local network if I need a graphical display. You just need power and a network connection ...and permission from your school IT admin guys. This also teaches your class about networking concepts - like SSH and FTP.

    Also do you realise that you can set up multiple accounts on each SD card?



  3. Difficult to answer.

    Bare minimum:
    30 x Pis
    30 x HDMI to VGA cables
    30 x Micro USB power supply
    at least 30 x 4GB SD Cards ideally more
    30 x earphones
    15 x earphone splitter cables

    Approx 2.5k

  4. 2.5k isn't a lot compared to to the price of buying 30 PC's and for this purpose it seems that the Pi is as good if not better than a PC. It is the lack of HDMI/DVI ports that's making this a pricey proposition. Something we should all be thinking about for future PC purchases.

    1. Do you make decisions on whole school PC equipment purchases? I have no say in how money is spent on the network infrastructure or what is ordered. Our dept budget covers the costs of text books, and stationary.

  5. "The hidden costs" would imply someone was/is hiding the cost from you.