cyber-dojo at Bristol Docker meetup

Here's a video of a short presentation I did (at the inaugural Bristol Docker meetup) explaining cyber-dojo and how it uses Docker. The projection is mostly invisible I'm afraid. The security flaws (such as running the containers as root) have now been fixed.

the cyber-dojo test view

  • click it to run your tests
  • the 'file' opens and displays the result
  • a new right-most traffic-light appears

Click any traffic-light to open the history view
red - the tests ran but one or more failed.
amber - the tests did not run, eg syntax error.
green - the tests ran and all passed.
the tests did not complete in 15 seconds. Accidentally coded an infinite loop? Too many concurrent cyber-dojos? Lost your network connection?
the total number of traffic-lights (in the most recent traffic light's colour).
a pie-chart indicating the number of red, amber and green traffic-lights so far.
your animal. Click this to open a dashboard view.

  • click to create a new file
  • click to rename the current file
  • click to delete the current file
  • click a filename to open it in the editor
  • the file is read-only


  • Alt-T runs the tests
  • Alt-O toggles to-from the file
  • Alt-J cycles forwards through the 'top' files (above )
  • Alt-K cycles backwards through the 'top' files (above )

search and replace

Start searching == Ctrl-F / Cmd-F
Find next == Ctrl-G / Cmd-G
Find previous == Shift-Ctrl-G / Shift-Cmd-G
Replace == Shift-Ctrl-F / Cmd-Option-F
Replace all == Shift-Ctrl-R / Shift-Cmd-Option-F
Jump to line == Alt-G

evidence for pairing effectiveness

When I run a cyber-dojo I always ask the participants to work in pairs, two people per computer. I've been doing some research on pairing and I've come across a book called Visible Learning by John Hattie. It's a synthesis of over 800 experiments and papers relating to achievement in schools. On page 225 there is a section called The use of computers is more effective when peer learning is optimized. It reads, and I quote...
  • Lou, Abrami, and d'Apollonia (2001) reported higher effects for pairs than individuals or more than two in a group.
  • Liao (2007) also found greater effects for small groups (d=0.96) than individuals (d=0.56) or larger groups (d=0.39).
  • Gordon (1991) found effects were larger for learning in pairs (d=0.54) compared to alone (d=0.25).
  • Kuchler (1998) reported d=0.69 for pairs and d=0.29 for individuals.
  • Lou, Abrami, and d'Apollonia (2001) reported that students learning in pairs had a higher frequency of positive peer interactions (d=0.33), higher frequency of using appropriate learning or task strategies (d=0.50), persevered more on tasks (d=0.48), and more students succeeded (d=0.28) than those learning individually when using computers.
What do the numbers mean? Quoting from the front of the book...
An effect size of d=1.0 indicates an increase of one standard deviation on the outcome - in this case the outcome is improving school achievement. A one standard deviation increase is typically associated with advancing children's achievement by two to three years, improving the rate of learning by 50%, or a correlation between some variable and acheivement of approximately r=0.50. When implementing a new program, an effect size of 1.0 would mean that, on average, students receiving the treatement would exceed 84% of the students not receiving that treatment.
Of course, things are rarely absolutely black and white, but these are impressive numbers.

  • Lou, Y., Abrami, P.C., & Apollonia, S. (2001). Small group and individual learning with technology: A meta-analysis. Review of Educational Research, 71(3), 449-521
  • Liao, Y.K.C. (2007). Effects of computer-assisted instruction on students' achievement in Taiwan: A meta-analysis. Computers and Education, 48(2), 216-233.
  • Gordon, M.B. (1991). A quantitative analysis of the relationship between computer graphics and mathematics achievement and problem-solving. Unpublished Ed.D., University of Cincinnati, OH.
  • Kuchler, J.M. (1998). The effectiveness of using computers to teach secondary school (grades 6-12) mathematics: A meta-analysis. Unpublished Ed.D., University of Massachusetts Lowell, MA.

facilitating a cyber-dojo tips

When I'm facilitating a cyber-dojo with a new group here's how I typically start:
  1. I suggest that developers habits and thinking is strongly influenced by their development environments. If you use Eclipse to develop software then when you use Eclipse your default mentality is one of development. Not practising. Since we're practising, we deliberately don't use a development environment.
  2. I point out that cyber-dojo is not a personal development environment, it's a shared practice environment. In a development environment it makes sense to have tools such as colour syntax highlighting and code-completion to help you go faster so you can ship sooner. In a practice environment it doesn't. When you're practising you don't want to go faster, since you're not shipping anything. You want to go slower. You want your practice to be more deliberate.
  3. I observe that since it is so different to a development environment, participants may feel some slight discomfort when first using cyber-dojo. This discomfort is also deliberate! Discomfort can bring learning opportunities.
  4. I do a short demo explaining...
    • the files on the left side
    • the initial source files bear no relation to the exercise
    • the test button
    • the output file
    • the meaning of the red, amber, green traffic lights
  5. I ask the participants to enter their dojo in pairs. Pairing is an important part of the learning. Occasionally a few choose not to pair (and that's fine) but most do.

the cyber-dojo history view

The history view shows the code for any traffic-light for any animal.
For example, this is the kangaroo's 96th traffic light.

Click on any traffic-light on the title bar to navigate directly to it.
The current traffic-light is marked with an underbar.

moves to the previous animal (if there is one).
the current animal.
moves to the next animal (if there is one).

moves backward one traffic-light.
the current traffic-light number (in its colour).
moves forward one traffic-light.

diffs are shown
moving to the previous/next animal moves directly to their first traffic-light.
diffs are not shown
moving to the previous/next animal moves directly to their last traffic-light.

the current filename.
click to auto-scroll its next diff-chunk into view.
the number of lines deleted from the file.
click to toggle the deleted lines on/off.
the number of lines added to the file.
click to toggle the added lines on/off.
the file's diff
deleted lines are in red
added lines are in green

downloads the currently displayed traffic light's files together with a manifest.json file ready to use these files as a custom starting point.
forks a brand new cyber-dojo, with its own id. The new cyber-dojo's starting files will be copied from the currently displayed traffic light.
reverts the files of the animal that launched the history diff to the files in the currently displayed traffic light.

the cyber-dojo dashboard view

Each horizontal row corresponds to one animal and displays, from left to right:
oldest-to-newest traffic-lights. Click on any traffic-light to open a history view showing the diff for that traffic-light for that animal.
total number of traffic-lights (in the most recent traffic light's colour). Click to open the history view in non-diff mode showing the animals current code.
a pie-chart indicating the total number of red,amber,green traffic-lights so far.
the animal. Click to open the history view in non-diff mode showing the animals current code.

  • when checked the dashboard auto-refreshes every ten seconds.
  • turn auto-refresh on during the coding.
  • turn auto-refresh off during the review.

  • when unchecked the traffic-lights of different animals are not vertically time-aligned.
  • when checked each vertical column corresponds to one minute and contains all the traffic-lights created by all the animals in that one minute.
  • if no animals press their button during one minute the column will contain no traffic-lights at all (instead it will contain a single dot and be very thin).

If available, displays slightly more information about the most recent non-amber traffic-light of each animal, usually the number of passing and failing tests.
Downloads a .tar.gz file of all the traffic-lights (intended for server administrators).