Blog Archives

Checksums (and some nice Python)

9/24/2015

I am a great believer in making use of the programming skills we teach students and applying them where possible in their lives and also in their studies (and there are some great ideas for cross curricular links!) My Year 8 students are currently working on programming a quiz in python so that our Year 3 students can take a computerized test using the code that our own students have developed!

Calculating checksums is not too difficult but it is a mundane activity so why not make this a practical task?

The first way you can really check that students have understood this concept is by creating a spreadsheet to do the hard work for you (example shown below)

A much better way for computer science student is to plan out the flowchart and then actually code the solution to output the correct checksum from any given input (my example output is below:

The full program and spreadsheet can be downloaded from here and the actual code is below for easy and quick reference!

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Parity Exercise

9/23/2015

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Error checking is not the most interesting subject to teach but this exercise is one way to ensure students understand and can use the concept of parity (odd and even).

Once students have been shown (and understand) how a parity bit works, move on to looking at the parity Byte which will allow specific data errors to be identified. Check understanding by creating your own parity exercise (using the spreadsheet) to double check the maths and then get the students to create their own parity puzzle which they can then swap with a partner for their partner to check and find the error.

The first time through, I ask the students to specify the type of parity used when creating the puzzle.
The second time through, I ask the students to keep the type of parity they used to themselves (so that their partner has to work this out themselves)
The third time, I ask the students to add more than one error to see if there can also be detected.

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Computing - Batch File Programming

9/16/2015

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Being the age I am (and learning to use computers from the very distant days before we had any graphical user interfaces), it can be amazing to today's students that a great many tasks can be accomplished just using a command line.

Skills like writing batch files to backup documents or do other tasks automatically can be very useful! When I last had a problem with a hard disk (just a few weeks ago) and the operating system on my laptop failed, it was the good old command line that enabled me to very quickly get the data off the old hard disk!

This week, we looked at creating a batch file to output a picture of the students' choice using just a few commands (but this taught a little bit of command prompt use and also how to create those all important batch files!

The basic program you can see below

@echo off
color 0e
echo (insert your picture text here with an echo for each line)
pause

All students need to do is to find a picture to encode and copy and paste that data from this website into a text document (using the code above and then renaming to a .bat extension) and some very nice artistic effects can be seen! A nice student created example of a minion is shown on the right!

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Computing Unplugged - Count on your hands to 1023

9/11/2015

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Teaching number systems (and in particular Binary) is not the most engaging subject for Year 7 students on a Friday morning but I managed to pique their curiosity and incredulity by asking them how it might be possible to count to more than 10 using just your fingers.

One student suggested using her toes as well (to count to 20) and another suggested using the three parts of each finger to get to 30!

This was a great way to introduce the concept of Binary and the ability to count to 1023 using both hands (or 31 if just using one hand) and then a simple presentation (using lights being turned off and on) showed actual counting in binary and how it works.

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The Zen of Teaching Computing without Computers Part 1

9/3/2015

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It might sound strange (and even a tad ludicrous) to consider teaching computer science without actually using computers! While being passionate about computing and IT in education, too many times have I seen some teachers using technology just too much! As part of reflective practice, it is vital to ask some questions about using technology and use technology where it bests adds value and enhances learning (which is something it can do very well when used appropriately).

It is sometimes very useful to take a step back and but the computers to one side and think about teaching computing unplugged (and there are some great resources out there).

One of my favourite activities at the moment is from TEACHING LONDON COMPUTING which has a Tour Guide Activity where students need to plan a trip around a city, starting and finishing at one location and visiting every other location once! This is an example of creating an algorithm that is a simple sequence of instructions to do in order and also allows students to check an algorithm and see it definitely works by following it step by step on paper. This activity leads on to the Knight’s Tour Activity which looks much more difficult, where a Knight on a small and modified chessboard, has to start and stop on the same square and also visit every other square on the board. The solution to this puzzle amazed my students and taught them a valuable lesson about computational thinking.

For an overview on how this type of puzzle can really enhance students thinking, take a look at A Brief Tour of Computational Thinking: The Knight’s Tour and Other Puzzles by Paul Curzon from Queen Mary University of London.

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Checksums (and some nice Python)

Parity Exercise

Computing - Batch File Programming

Computing Unplugged - Count on your hands to 1023

The Zen of Teaching Computing without Computers Part 1

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