The Weekend Experiments – Gravity

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Do you remember those days at school when your physics teacher would tell you that the strength of gravitational acceleration is 9.8 m/s2? You just took it on blind faith that that was the strength of gravity right? Well, in the first of my Weekend Experiments series we are going to look at a very simple experiment anyone can do to find the strength of gravity in their local area (or planet). All we need is some string, a weight and your mobile phone to do some timings and a few calculations.


Myself and students of St Saviours High School, Leribe, Lesotho performing the Pendulum Investigation – 2010

What you need

A long piece of string – the longer the better

Somewhere to hang it from

A stop watch – just use the one on your phone

A weight – even a small stone will do

And a measuring tape or metre stick

Calculator – again use the one on your phone if desperate

What you do

Tie the weight to the end of the string and hang the piece of string up from the other end (remember the longer the string the better).

Measure the length of the string in metres to the nearest mm if you can.

Let the weight rest down and give it a little push – just a few cm will do.

The weight should now start moving back and forth in a pendulum motion.

Using your stopwatch we need to time how long the pendulum takes to go back and forth (We call this an oscillation). Human beings don’t have great reaction times so I suggest you time 10 swings or more in one go and find an average.

The Calculation

So here comes the maths – don’t freak out.

g = L4π2/T2

L is the length of your string in metres

π is that circle thing equal to 3.142 (approximately)

T is the time taken for one swing

An example

L = 3.56m

T = 3.8 seconds

g = 3.56 x 4 x 3.142 x 3.142 / (3.8 x 3.8)

and I get..

g = 9.73m/s2

not a bad answer with just some basic equipment!


QR Code Treasure hunt

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20140128_123901I don’t know where I got this interest in QR codes from as they are not that popular yet in South Africa. On recent trip to the UK I found them often in newspapers linking to product websites and wondered how difficult would it be to make my own. A lot of students now have phones capable of reading QR codes so I thought it would be a fun to make a QR code treasure hunt. I decided to only inform the principal of the school and no member of staff to keep it as secret as possible. The interesting thing about QR codes is the it’s not like a normal treasure hunt as there is an air of mystery about these unusual symbols. You don’t tend to notice QR codes as much as normal text and it was a lot of fun hiding them around the school. We had eight base stations in total and I designed the clues so that it wouldn’t matter which QR code the students scanned in first with a loop of 8 different clues. With each clue the students would gain an extra letter and these letters would all make up a master key word. One of my favourite hiding places for hiding the QR codes was behind one of the basketball hoops. If you are interested in making your own QR codes there are plenty of apps and also many free online QR code was the website that I used to make my QR codes as it outputs the QR codes as simple png format that can easily be printed


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Electronics Club and Sumbandila

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sumbandila arduinoI run an extra-mural electronics club and we were lucky enough to get hold of some Arduinos – credit card sized computers that can be programmed from a PC and used in just about any project you can think of. The Students and myself basically get to tinker away with electronics which is awesome – watch this space for project updates. I also work with Sumbandila, a non-profit organisation in the field of secondary education which provides an educational outreach programme to impoverished rural children in Limpopo. Sumbandila ran a holiday school a few weeks ago and we got the students programing the Arduinos too! It was fantastic. We built a little traffic light LED shield (a circuit that mounts on top of the Arduino) and the students could program it themselves. It was very impressive to see these kids going from having a very limited knowledge of programming to getting all the LED traffic lights flashing in order – with minimal input from myself. Arduino is an open source system I would recommend to any ICT or Science department. Give it a go!

What is the future of education?

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Where is education going? I’ve been teaching for seven years now and I have noticed some big changes even in my short time in the profession. I started teaching in the UK in 2006 but moved to South Africa in 2011. In South Africa many people seem to be interested in home schooling. They feel the state system has let them down and that even private schools do not give them what they need. With the plethora of apps, past papers and YouTube videos that are widely available online there is the feeling that they can go it alone. Is that wise? Nothing can really replace the experience of a professional teacher who is trained in pedagogy, knows their subject and knows how students tick.

Technology has really changed teaching. A lot of the time I am facilitating learningBUb8ASvIAAApEu5 rather than doing the teaching myself. I don’t necessarily see this as a bad thing. Students need to go at their own pace, to be independent learners and need to gain the key skills that will set them up for life. I recently discovered which is a fantastic site that can guide students through a multitude of problems in Mathematics and Science. They are set at the students individual level and I would strongly recommend any parents to push their children to give it a go, it’s sure to help.

What I do love about teaching with modern technology is the collaborative effort that you get when working with other teachers online. I joined when I started my teaching career. To begin with I was simply grabbing as many resources I could in order to keep my head above the water as a newly qualified teacher but I soon started uploading my own worksheets and Powerpoints – some have been downloaded over 50,000 times!! Amazing to think that my resources are being used in so many different classrooms. It even started to get a bit addictive.. The feedback from other teachers around the globe was very positive and this spurred me on to do more…