Don’t accept corrupted files

With greater reliance on technology for student work, we run into the possibility that there can be technology issues with student work – connection problems, version issues, lack of access, etc. Though as the technology, and availability thereof, increases, these issues seem to be declining.

But there is one issue that seems to be on the increase, and that is students having problems with files becoming corrupted and inaccessible. As supportive educators, we don’t want to be punitive if there are legitimate issues. But having been around the sun a few times, I know a statistical rat when I smell one.

As computers become faster, storage is ubiquitous, and there is less and less saving to removable media the opportunity for files to become corrupted by accident is declining. It can still happen, if for example a flash drive is removed while a file is being copied or saved, or the computer crashes while a file is being saved, but since saving a file is so fast, the chances of this are very, very slim. So what’s going on?

Mainly, this: There are plenty of sites, and YouTube videos, and how-to’s about corrupting your own files so they can’t be opened. Then it is just a matter of acting surprised, and bingo! The teacher asks you to please re-do the work as quickly as possible, giving you extra time to complete the work.

Well, I’m on to them, and now so are you.

So let’s look at a few ways files can be corrupted, and how to recognize a corrupted file, and how to tell the contents of the file (I am a PC user, not a mac user, so I will focus on what I know, but I’m sure if you are a mac user you can find someone who can help you out similarly).

1. Changing the file type. This one is dead easy, but also very easy to detect. The idea is to take a file – such as an image or a video file, or an exe or whatever you have around, and simply change the extension to .docx or .pptx instead of .jpg or whatever it was. Since most users don’t even have the file extensions visible, this one is fairly effective. The application just chokes, and is unable to “repair” the file. The solution? Open the file with notepad. You can just open notepad and drag and drop the file in. While most of it will look like gobbledygook, there will be clues, mainly in the first line, where you may see something like “PK    »¬fB” or “JFIF” or some other clue. A quick Google search may help you identify the file type – PK is a zip file (or an Office document – since office docs are a collection of information files saved together as a zip), JFIF is a jpg image, and so on. Try changing the file extension and opening in another application. Other clues lie elsewhere in the file – Word documents may end with a sequence like:

“word/numbering.xmlPK-    ! ÷ÝJÆ¿ Q  °Z word/people.xmlPK-    ! ©Ó¢Ùñ ‰  œ\ customXml/item1.xmlPK-    ! —IqE   æ` word/fontTable.xmlPK-    ! õøÍ ¾  [c word/commentsExtended.xmlPK-    ! $ï¶D ÿ  _e word/webSettings.xmlPK-    ! ¶Ëëš\ ˜  ¤f docProps/core.xmlPK   — 7i”

Which clearly identifies it as a word doc. So if you get something purporting to be a “corrupted” word doc, and it has none of these, then it is likely not actually a word doc.

Powerpoints also have clues, like: “ppt/slides/_rels/slide9.xml.rels¬MKÄ0†ï‚ÿ!Ìݤ-”‹lº<Éú†dš›2Y±ÿÞˆ—-”. If there is nothing like this, then it probably isn’t a powerpoint.

2. Corrupting the header. It is easy enough to delete a few characters from the start of a file (using Notepad as above, for example), which will render it completely unusable. However, if you can go into the file in notepad as above, you should be able to see if it is the right type of file. If the internal clues are still there but that first line with the file info is missing, it probably had that info deliberately deleted. Unfortunately, it is almost impossible to recover a file corrupted in this way. But I’m working on it…

3. Online tools. Yes, there are tools online specifically to mess up your files so they data cannot be retrieved. A hallmark of these tools is that they overcorrupt, so the file is comletely unrecognisable. Compare the screenshots below of a powerpoint file and the resulting corrupted file:





Though hard to prove, but there is no way for an office document or powerpoint to wind up looking like that by accident.

So, with this information,  what do we do?

Firstly, there are proactive strategies such as having students submit drafts regularly, and requiring students to make backups. Also, you can have students use tools such as Google Drive – where the back end file is inaccessible and all changes are tracked –  in order to minimize the risk of file corruption (intentional or otherwise).

Secondly, arm yourself with knowledge of what tricks people may be up to. If you suspect a file has been tampered with, drop it into notepad and have a look, or bring it (and a copy of this post) to your IT department and have them look at it.

Lastly, and perhaps most importantly, keep the lines of communication open, and let students know that legitimate reasons for a delayed submission are open for discussion, so that maybe they will never feel like they have to resort to this.


Trouble with Static Kits

My grade 9′s are doing static electricity at the moment, and I am experiencing some weirdness and frustration with the kits I have. Firstly I have a combination of new and old kits, but they all come with a standard collection of items – glass, ebonite and plexiglass rods, fur, felt and silk pads, and a few other odds and ends. My problem is I am finding it hard to reliably, and consistently, get a good charge, especially a positive charge.

The instructions usually suggest rubbing glass with silk to produce a positive charge on the glass. This, in my experience, never works. Last year I discovered that rubbing the glass rod with the plastic baggie the kit comes in worked well – but with the new kits I just received that doesn’t seem to work, no idea why not.

And then there is the mysterious flip-flopping plexiglass. Acrylic when rubbed with fur should become negative – but when I held it up to a negatively charged electroscope, the leaves dropped – indicating a positive charge. I tested it with a positively charged electroscope, and the leaves spread apart, confirming the positive charge. Okay, so it’s positive. But then when I tried to demo that it was positive, it suddenly had the opposite effect. It was bizarre, and my students were totally confused – as was I.

I love a teachable moment as much as the next guy, but when the message seems to be that science is arbitrary and unpredictable, I don’t think it is the right lesson to convey. I hate it when that happens.

Back up after a malware attack

This site was shut down for a few days due to a malware infection. Both Google and my host provider flagged the site and alerted me to the problem, which was ultimately solved by deleting the entire site, re-installing fresh, and restoring the database. As a result the site is sporting a new look – which I am trying to decide if I like or not.

Anyway, it was a learning experience, and what I learned was a) backup regularly and b) restoring a wordpress site is not hard, if you follow a).

If there are any missing graphics or broken links as a result of the re-build, please let me know.



Gardner: ‘Multiple intelligences’ are not ‘learning styles’

I am pleased to see this article in the Washington Post: Howard Gardner: ‘Multiple intelligences’ are not ‘learning styles’. Howard Gardner is the most prominent voice in the area of multiple intelligences, an idea that has been co-opted by proponents of learning styles, which I have already stated I don’t believe in. The article clarifies Gardner’s stand on what he means by multiple intelligences, namely that the brain functions as a set of connected but autonomous processors. Gardner clearly distances himself from (and actually chastises) those who misinterpret his work.

A little Google docs win – almost

Today I played the Deer Game with my grade nines to illustrate population dynamics, limiting factors and carrying capacity. We usually iterate a dozen or so times, counting and recording the dear population on each turn, and then enter the results on a spreadsheet and graph it when we get back to the classroom.

Well, this year I did something a little different. I created a Google sheet, and created a chart based on a set of (presently empty) cells. I left this display up in the classroom when we went outside. During the game, I recorded the results each round on my phone, in the same spreadsheet. So when we wrapped up and went back to class the graph was already waiting for us on the screen. As a bonus, we ran this activity with two classes combined, and both classes could see the same data.

This was a great little timesaver, and I would rave about it, except for one little thing – scatter plots. The scatter plots in Google sheets do not show connecting lines or curves, just the scatter points. For this activity a line graph is sufficient, because we are iterating equal intervals, but uncovering a glaring hole in the capabilities of Google sheets slightly tarnished my esteem for this set of tools.

How do you science?

Yesterday in class one of my students asked “am I sciencing right?”

After giving him a high five for cleverness, I got to thinking more seriously about that question. In courses like Drama, Art, Music, and Physical Education the students spend a minimal amount of time learning theory, and maximal time practising it. Doing it.

In Science, at least in the introductory courses, there seems to be so much emphasis on basic facts that there is little time left to do science, or as my student would to science. Now, admittedly, there is several centuries worth of background to what goes on in our daily lives. Even up through much of my undergrad studies my courses were pumping me full of background knowledge, with little emphasis on doing science. It wasn’t until my undergraduate thesis and grad school that I got to actually science.

Science is often touted as a subject that requires inquiry, but most science courses actually don’t. Researching facts is an important aspect of science, but it is the preliminary legwork before the actual science begins. When we actually science, we are actively investigating and experimenting, troubleshooting, problem solving, analyzing, and synthesizing. Using our brains, designing, building, testing.

I realize there are some programs, such as the modelling method, that allow (or require!) students to science in high school, but availability and training for these types of programs is not (yet) widespread. I think it’s time to spread the science. If you implement a course, particularly an introductory science course at any level, that is built on students actively doing science, I would like to hear from you. How do you science?


For students, que sera sera? Maybe.

I have long posited that the real success of education cannot be determined in the short run. How a student does on the next test is not really a measure of the effectiveness of teaching. We really need to look down the road at how students are faring a year, or two, or five later to get a real sense of  how what we have taught has been useful or effective.

A recent reunion, where I met students from as far back as 13 years, gave me a (admittedly somewhat uncontrolled and subjective) sample of how my students have done. And you know what? There is not really a strong correlation between how they did in my classes (or school in general) and how they did later. While many students who did well in school continued to do well in university and career, it is also the case that many who were “troublemakers” in high school went on to be very successful (some even becoming teachers!), while some who were excellent students in school went on to perfectly uneventful and mundane post-secondary study and careers.

Frankly, it looks like students will go on to do what they do, with or without us. While we may have some influence – a little inspiration, a little nudge, exposing them to things they might otherwise not have seen, I think it is naive to think that what we teach them (or try to) determines their future.

So how do I feel about this? Does this make me feel like what I do has no meaning or value? No. I think this means that I can help provide a foundation for the majority of my students – including some who may not actually think so at the moment. I can act as a role model, foster an interest in  (and understanding of) science, and help provide them with tools that they can use in later life. But it also means that if I decide to stray from a proscribed curriculum to allow them to pursue what might be construed as “peripheral” material, it probably won’t disadvantage them in the long run. Those who would be successful will still likely be successful, and those that wouldn’t be, well, just maybe I can help them  choose their own destiny, or point them in a way they hadn’t thought of before, and just maybe that can improve their chances of finding success.

The indirect lesson we mustn’t forget

I was at the Google Apps for Education Summit a few weeks ago. Lots and lots of great stuff, interesting talks, interesting discussion between talks. But there is one thing I learned that I really REALLY must not forget as I plan my courses for next year.

You see, the GAFE summit was held at a high school in Kitchener, and I spent two days sitting in chairs, at desks and in the auditorium. And dammit, it was uncomfortable. I mean ass-numbingly knee-bangingly miserable. And yet, when we see kids being fidgety in class, we often think it’s because they can’t sit still.

The old Golden Rule is do “unto others as you would have them do unto you”, and I suppose the flipside is also true – don’t do unto others what you wouldn’t want done to you. I would rather not have to sit in a hard chair at a small desk all day. So I will try my best not to make my students suffer that fate either.