My Week Ending May 13, 2018


Readings (You can follow my daily readings as they happen here.  Here are a selected few from the past week.)

  1. It won’t be long now until the end of the school year.  The storage of computers is always an interesting challenge.  This article talks about care and storage of Chromebooks with a focus on maintaining battery life.  It’s good advice for everyone.  I wonder if anyone would be brave enough to do what is recommended at the end of the article.
  2. For some reason, I was drawn into a discussion about the best stylus for a computer for drawing things.  I’m not sure that I would be able to offer anything that resembles good advice for someone who is an artist.  But, I did learn about this site so the exercise wasn’t wasted.
  3. This is not a Chamber of Commerce moment for Hawaii.  Watch as a flow of lava nails a car.
  4. Speaking of wrecks – we’re in for an election.  MacLeans is a good resource for daily updates.  Do politicians live up to their election platforms?
  5. Kudos to Halton DSB for the launch of their districts portable application.  It’s a great way to meet their community where they live.  The ability to push via an app as opposed to the traditional way of people visiting a website is an interesting approach.  Shouldn’t all districts do this?
  6. The demonstration of Google Duplex got a variety of responses.  Of course, there’s the Wow factor.  But the privacy issue got a big uptake forcing an update to let us know that it will identify itself as a bot if it ever comes to fruition.
  7. Given how the 2016 election worked out in the US, I think we’re overly suspicious of things in Ontario.  That’s a good thing; question everything.  Why would anyone think hiring actors be a good idea?  If you can’t get enough people that legitimately support you to show up, you’re in trouble.  At least it didn’t result in fighting so that’s always a good thing.
  8. I can’t imagine a digital world without passwords.  But, Firefox can.
  9. I can’t get over how many people get nailed by Border Security by having bad things stored on their phone.  In a cloud world, why wouldn’t you put it up in the cloud and delete it from your phone?  This ruling indicates that there is hope for those who aren’t smart enough to do that.
  10. Here’s a wonderful collection of inspirational quotes for Education Week.  Add to your profile, put on your blog, share them with everyone.


Blog Posts on doug … off the record


voicEd Radio

My on demand page can be found here.  The latest edition features blog posts from:


Technology Trouble Shooting

Chrome OS – A recent update to Chrome OS left me with an interesting problem.  Normally, I can just flip the display around and use the touchscreen to run Android applications.  That stopped working.  I ended up having to launch via the keyboard and then flip the lid.  I figured it was me so rebooted a couple of times with no success.  It turns out that it was the Chrome OS.  An update later in the week fixed it.

A Tale of Two Stores – Last weekend, I spent some time at the Eaton Centre.  One of my visites was to the Apple Store.  What a zoo!  It was packed with people obviously in love with the technology.  My first thought was a religious revival.  Whatever Apple is doing, they’ve got people onside.

Then, I went to the Microsoft store.  It was completely different.  There was all kinds of room to move around and you could actually talk to a salesperson without having to shout over the din.  I got to play around with a number of different Windows computers and couldn’t help but notice that the screens were really brightened far more than any computer that I own because I worry about battery life.

The Microsoft devices were terrific to operate.  There’s just the price thing.


Video of the Week – From “This Week in Ontario Edublogs”

Every week, one of the blog posts inspires me to select music to go with it.  Lisa Cranston’s post about Outdoor Classroom go me thinking of Led Zeppelin’s “In through the Outdoor” album and this song.
My Favourite Photo This Week

Right out our front door.  Happy Mother’s Day

Screenshot 2018-05-13 at 10.41.28


Thanks for reading.



Whatever happened to …

… ROT13?

Thanks to Alfred Thompson for this idea.  It came through a Facebook post.

Screenshot 2018-05-11 at 11.04.01

So, I took the bait.  It had indeed been a long time since I thought about ROT13.

I do remember in elementary school going to school with a set of twins.  At times, they had their own language.  They would talk back and forth and nobody, especially the teacher, could understand what they were saying.  It infuriated her that these two were talking “in code”.

We were no better with passing notes to each other.  Of course, we didn’t want the note to be intercepted and, if it was, we had our own “code” to make sure that the message wasn’t read.  It was only the high level type of security that someone in Grade 5 could develop.  We would just shift the letter one digit to the right.  So, DOUG would become EPVH.  All the recipient would have to do is uncode it by selecting the letter to the left.  We were so clever; that dumb teacher would never figure it out.  Ah, we should have just quit while we knew everything.

It wasn’t until I studied Computer Science (and later taught it) that the beauty of encoding a message was really appreciated.

At university, we had a number of problems to code / decode strings of characters using various algorithms.  It wasn’t until I actually taught Computer Science that I realized that ROT13 was “a thing”.  And, it was a beautiful thing to have.  The concept could be used in a number of ways.

The ROT?  It is short for “rotate”.  In essence, we were doing ROT1 in Grade 5 – rotating by one letter.  ROT13 is a very special version of this.  Since there are 26 letters in the alphabet, ROT13 meant rotating half-way through the alphabet in coding and decoding.


One of the topics to be covered was the breaking of the code used by the Germans in World War II.  Of course, it involved an appreciation of Alan Turing but ROT became a hands on activity as we did our own messaging.  I remember one group of students creating their own cracking device with a couple of sheets of paper.

But there’s more.


If you create an array, say LETTER, of 26 characters, then you would assign LETTER(1)=”A”, LETTER(2)=”B”, etc.  to encode / decode, it was just matter of adding or subtracting 13 from the index to make it work.  And, of course, there was the challenge of what to do when you add to the index and it goes above index 26 or or subtracting leaves it below index 1.


Every computer programmer knows that CHR(65) is the letter A.  Actually, the whole ASCII table is just one big array, but you don’t mention that until you’re done.  So, to encode the letter A with ROT13, it’s just a matter of replacing it with CHR(78).  No need to work it out – it’s the letter N.


In another variation of a theme, forget all the fanciness of using an array.  Just go with the string itself.  DOUG  The algorithm involves determining the length of the string and then going through things extracting one letter at a time, rotating it by 13, and adding the result to an output string.  When you’re done, the message is encoded.

For some reason, this really caught student interest and led to some interesting conversations.

“If people know that it’s ROT13, it’s just as easily decoded”  (Yep)

“What if we double ROT13ed it?”  (Short discussion on the inadvisability of doing that.  In retrospect, I should have let them do it as it would have led to a better discussion – how do you know if your program works when it gives unexpected answers?)

“What if we didn’t do ROT13 but something else?”  (For every problem, there’s a solution)

“What if we ROT13 the first letter, ROT14 the second, and so on”  (Liking this line of thinking)

“What if we ROTted with a random number?”  (Slick.  I knew we taught random numbers for some reason)

“What if we ROTted with a seed from the computer clock?”  (I made the mistake of showing them how to read the computer clock and using some of it as random numbers.  When the only tool you have is a hammer, everything looks like nails)

And some good problem solving.  “We’ll send the message via email and send the decryption key in another email. ”

“What if someone gets both messages?”

“We’ll ROT the key”.  (They now own a new hammer)

It led to good discussions too.  We were using QNX as an operating system then and I created a few dummy accounts and showed them that the passwords were stored in straight ASCII.  They were appalled!

It led to some enhancements too.

“Sir, we didn’t want to be limited to the letters A-Z so we modified it for lower case, numbers, special characters, …”  (Hey, this course teaches itself)

These days, encryption is such an important topic.  As Alfred notes, there was an attempt in some newsgroups to stop people from giving away spoilers by ROT13ing them.  You could easily decode them if you really wanted to know the answer or just ignore it if you didn’t.  ROTting is a relatively easy mental exercise.  But, I’ll be honest.  I can’t remember the last time I’ve seen it in use.

But the conversation about encryption continues.

With online banking and other things, secure connections are so important.  Of course, the algorithms are so more sophisticated than ROT13 but you have to start somewhere.

For a Sunday, what are your thoughts?

  • Did you ever pass notes in school?  Did you have a way to make sure that they or their message they didn’t fall into the wrong hands?
  • Do you double and triple check for a secure connection when buying things online or doing banking?  Report cards?
  • Do you use EFF’s https everywhere extension to ensure that your connections are encrypted?
  • If you’re teaching students, what steps do you talk about to teach them about privacy online?
  • Computer Science teachers – do you have any interesting lessons about ROT13 or encryption to share?

As always, I’d be most interested in your thoughts?  Please share them in the comments below.  Bonus – you don’t have to write your own ROT13 these days – check out this site –

This is part of a regular Sunday series that can be accessed here.

Do you have an idea for a topic like Alfred did?  Let me know.  You can use this Padlet for the task.

Happy Mothers’ Day



OTR Links 05/13/2018

Posted from Diigo. The rest of my favorite links are here.