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Perimeter Institute – EinsteinPlus 2016 – Day 3⤴

from @ stuckwithphysics.co.uk

Day three began (after breakfast) with a session on Quantum Mechanics. The session was based around the 'Investigating the Nature of the Electron' activity from the Perimeter Institute's materials on 'The Challenge of Quantum Reality'.


The first task, 'Classical Particle Behaviour', uses very simple apparatus - sand and a paper coffee cup, to model the behaviour of particles passing through two narrow slits - Young's slits experiment. The task asks students to make a prediction of what they will see, encouraging them to explain their reasoning before continuing with the procedure of passing a small amount of sand through two narrow slits cut into the base of the cup.

As expected, two small piles of sand are obtained,

Perimeter Institute – EinsteinPlus 2016 – Day 3⤴

from @ stuckwithphysics.co.uk

Day three began (after breakfast) with a session on Quantum Mechanics. The session was based around the 'Investigating the Nature of the Electron' activity from the Perimeter Institute's materials on 'The Challenge of Quantum Reality'.


The first task, 'Classical Particle Behaviour', uses very simple apparatus - sand and a paper coffee cup, to model the behaviour of particles passing through two narrow slits - Young's slits experiment. The task asks students to make a prediction of what they will see, encouraging them to explain their reasoning before continuing with the procedure of passing a small amount of sand through two narrow slits cut into the base of the cup.

As expected, two small piles of sand are obtained,

Perimeter Institute – EinsteinPlus 2016 – Day 2⤴

from @ stuckwithphysics.co.uk

Day 2 of EinsteinPlus 2016 saw the group formally welcomed to the spectacular Perimeter Institute building after an equally spectacular breakfast. (There are two excellent bistros at PI, which provided the group with a fabulous range of meals over the week long visit. I'd say more, but there'd be a real danger of this becoming a food blog...)

The morning session was split into two -

  • Cosmology - this used an existing PI activity 'The Signature of the Stars' from their educational resource on 'The Expanding Universe' - using diffraction glasses observations were made of line spectra from a variety of gas discharge lamps. These spectra are used to identify the elements present in stars, in the Milky way and in distant galaxies. The spectra of light from distant galaxies shows the same spectral lines as stars in our galaxy, but the lines appear in slightly different positions, with longer wavelengths. This effect, known as Red Shift, occurs because the galaxies are moving away from us, and each other, at high speeds. Measuring the red shift for a galaxy can be used to measure its speed, which relates in turn to its distance from us. This effect was first observed in the early 20th century and used to formulate Hubble's Law - which states that not only is the universe expanding, but the further away from us a galaxy is, the faster it is moving. The activity includes data allowing the red shift of a range of galaxies at different known distances to be used to find their speeds. This data is then plotted it give a graph representing Hubble's Law, which gives an approximation of the Hubble constant and can in turn be used to find the age of the universe.

  • Gravitational waves - this used a newly developed activity based around the recent detection of Gravitational Waves at the Laser Interferometer Gravitational Wave Observatory (LIGO) facilities in the USA. The facilities use extremely large scale (~4km) laser interferometers to measure incredibly small expansions or contractions (~10-19 m - 1000 times smaller than the diameter of a proton) of the devices which occur when gravitational waves pass. There are many areas of physics and engineering involved in the development and operation of the LIGO detectors, from the solutions to Einstein's General Relativity which predicted the existence of Gravitational waves, to the intricate suspension of the mirrors sued to improve the sensitivity of the detectors - developed at the University of Glasgow. The activity centres around the properties of waves, and their behaviour when they undergo reflection - beginning with demonstrations of mechanical waves using a slinky. Observations of phase change upon reflection were developed upon and related to the operation of the interferometers at LIGO. These ideas were utilised in a hands on activity to simulate the paths of the laser light used at LIGO in order to find the nature of the light detected when the device is unstretched (no gravitational wave) and stretched. This task offers an excellent opportunity to link this part of the Advanced Higher physics unit on waves to a context which involves real, cutting edge physics.

LIGO unstretched

LIGO stretchedAfter lunch, followed a two more sessions -

  • Neutrino Detection - another new activity, this is based on the Nobel Prize winning work of Professor Art McDonald and his team at the Sudbury Neutrino Observatory (SNOLAB). The session began with an overview of the production of neutrinos in the sun and the difficulty in detecting these particles - the 'Solar Neutrino Problem'. The session continued with a description of the facility at SNOLAB and a hands on task modelling the detector using marbles, cardboard boxes and a baking tray. There was a great deal of discussion about this task, and the nature of the model to describe and explain neutrino detection. Consequently there was a shortage of time for the remaining tasks, dealing with real data from SNOLAB and the theory of 'neutrino oscillation'.

  • Dark Matter - this session used the 'Dark Matter Within a Galaxy' activity from 'The Mystery of Dark Matter' materials. The activity begins with a revision of the basic rules for circular motion and gravitation, using a range of data to find and plot the orbital speed of a star against its radius from the centre of its galaxy. These values, calculated from classical theory, do not compare well with observational data - implying that there must be more mass in these systems that we can not detect - Dark Matter. Whilst the part of the underlying physics of this task, circular motion, is beyond the scope of the Higher physics course in Scotland, it might be fair to use this as a practice data handling task which could be used to exemplify and reinforce the very brief mention of Dark Matter in the 'Our Dynamic Universe' unit.

The final session of the day was a keynote presentation delivered by Professor Avery Broderick from the University of Waterloo on the Event Horizon Telescope (EHT). This program uses nine existing telescopes across the globe and applies a technique known as Very Long Baseline Interferometery (VBLI) to improve the resolution at which images of very small objects can be made.

It is hoped that by improving the resolution for existing telescopes and including planned future telescopes in the gathering and processing of data, the EHT will obtain the first direct images of the event horizon for a black hole in our galaxy. Recent observations in the constellation of Sagittarius are thought to indicate the presence of a black hole with a mass around 4 millions time that of our sun. This black hole is of the right size and at the right distance for the EHT to be able to make observations that will allow an image to be obtained in the next few years.

The data gathered and images obtained by the EHT will allow for further testing of Einstein's theory of General Relativity, and provide a greater understanding of phenomena such as black hole accretion and plasma jets.

After this presentation and another excellent meal the group was offered a tour of the Perimeter Institute building, offering an insight into how the facilities have been designed and developed in order to attract and facilitate the work of some of the world's foremost theoretical physics (not to mention a very large number of teachers and students).

A selection of images of the building will be included in a gallery as soon as I figure out how to make it work...


Perimeter Institute – EinsteinPlus 2016 – Day 1⤴

from @ stuckwithphysics.co.uk

Earlier in the year I was delighted to receive an invitation to the annual Einstein Plus teachers' summer school at the Perimeter Institute in Waterloo, Ontario.

A total of forty two teachers from across Canada, USA, Europe and Asia attended the event, comprising workshops, lectures and visits from the 6th to the 12th of July.

Having registered and settled into our accommodation for the week, the first evening was given over to a delicious meal followed by a session of group 'ice breaker' tasks at the Hawk's Nest, Wilfrid Laurier University - one of two universities in the city of Waterloo.

One of the tasks was on the 'Process of Science' and involved the use of some small wooden cubes. Each of five of the faces carried a name and two numbers as shown in the images below.

Cube 1 Cube 2

Groups were asked to make observations, try to identify relationships and then predict what could appear on the blank face of the cube. Each group was able to complete all of these steps, but interestingly no two groups came up with exactly the same solution. All of the suggestions given were equally valid, given the evidence on which they had been based. This task made an excellent introduction to the idea of scientific modelling, a theme which would be returned to throughout the week.

Newton’s G-ball⤴

from @ stuckwithphysics.co.uk

'Newton's G-ball', marketed by Swedish company Mollic, is a simple electronic timing device which can be used to measure the the freefall time from its point of release to impact on a surface below.

It is available from a number of third party suppliers, including djb microtech and Better Equipped in the UK and Arbor Scientific in the US.

gballThe ball has an integral centisecond timer, which is primed by pressing and holding the button on the face of the timer. Releasing the ball starts the timer, which stops when the ball impacts upon a surface below.

If the height, h, through which the ball falls is known, and the time for the ball to fall, t, is measured, then g can be calculated using the formula -


Taking multiple measurements of the freefall time, t, over a range of heights, h, allows a range of values to be obtained for g.

The results below were obtained by my Higher Physics class on 9th June 2016.

h (m) t1 t2 t3 mean t (s) g (ms-2)
0.2 0.23 0.22 0.27 0.240 6.94
0.4 0.30 0.27 0.30 0.290 9.51
0.6 0.39 0.35 0.38 0.373 8.61
0.8 0.42 0.39 0.41 0.407 9.67
1.0 0.46 0.48 0.46 0.467 9.18

The results obtained are reasonably good, giving a mean value for g = 8.79 ms-2. Whilst this is in reasonably close agreement with the quoted value of 9.8 ms-2 given in the SQA data tables, discounting the obviously low value obtained for h = 0.2 m gives an improved mean value for g = 9.51 ms-2.

A quick analysis of the uncertainties in this data give the following -

Uncertainties in height, h (approximate reading/position uncertainty = ± 0.02 m)

h (m) uncertainty in h (m) % uncertainty in h 
0.2 0.02 10%
0.4 0.02 5%
0.6 0.02 3%
0.8 0.02 3%
1.0 0.02 2%

Uncertainties in time, t -

h (m) t1 t2 t3 mean t (s) random uncertainty in t (s) uncertainty in t 
0.2 0.23 0.22 0.27 0.240 0.017 7%
0.4 0.30 0.27 0.30 0.290 0.010 3%
0.6 0.39 0.35 0.38 0.373 0.013 4%
0.8 0.42 0.39 0.41 0.407 0.010 2%
1.0 0.46 0.48 0.46 0.467 0.007 1%

Uncertainties in g -

g (ms-2) mean g 


random uncertainty in g (ms-2)
6.94 8.79 0.55
8.61  % uncertainty in g absolute uncertainty in g (ms-2)
9.67  8% 0.70

This gives a final value for g using this procedure as -

g = (8.79 ± 0.70)  ms-2

However, an alternative graphical analysis allows an improved result to be obtained from the same data.

For this approach, the formula above was rearranged for h, giving -


A graph was plotted of h against t2, giving a good approximation of a straight line through the origin, as expected.

t2 (s2) h (m)
0.0576 0.2
0.0841 0.4
0.1394 0.6
0.1654 0.8
0.2178 1.0


Using the trendline function in Excel, a best fit line was added with its function included. The gradient of this straight line, which is equal to ½ g, is 4.91, giving a value for g from this graph - g = 9.82 ms-2.

Further analysis of the graph, using the LINEST function in excel, gave the following uncertainties -

gradient uncertainty in gradient % uncertainty in gradient
4.91 0.33 7%
g (ms-2) absolute uncertainty in g (ms-2)
9.82 0.69

This graphical treatment of the data gives a final value for g using this procedure as -

g = (9.82 ± 0.69)  ms-2

I have included the raw data, graphical treatment and uncertainties in the in the excel file below.

g ball

Digital Privacy⤴

from @ Through The Windae

 This tweet provoked a really interesting and helpful debate about digital privacy. https://twitter.com/athole/status/720345548780244992

I have been acutely aware of the many school Twitter feeds publishing names and images of pupils together. And this left me uneasy. I have experience of using blogs and blogging with classes since 2007. My class even won a competition way back in 2010. http://godzillasden.blogspot.co.uk

Currently at my school all classes are using ClassDojo and the Class Story very effectively. I pull a snapshot from each Class Story to share on Twitter @BearsdenPrimary and the school website https://blogs.glowscotland.org.uk/ed/bearsdenprimary/ , ensuring that this matches parental consent and that images and names never appear together. The digital leaders in my school are beginning to take more responsibility with the updating of the website and Twittter.

In summary, the discussion highlighted some really good examples of good practice and stimulated some deeper reflections of what we need to next in my school to include pupil voice in discussions around digital privacy.

  • @kirktonPS never include visuals of pupils and they always focus on the learning
  • other schools use image and no name, or name and no image
  • everyone agreed that too many schools included names and images together
  • the most important point raised was that about pupil voice. We ask parental consent but do we ask the pupils? (I’d say I honestly do this about 50% of the time, just now) Despite being evangelical about children’s rights and political literacy, I realised I had shamefully given this matter very little thought, in my eagerness to raise and boost the profile of the school, improve communication and share achievement and learning.
  • consider audience and purpose when and where posting (this is a strength for me)

Action points for the new term…

  1. raise the issue with the pupil voice groups and also with teachers to make them aware of pupil consent
  2. create a digital charter. We have begun to use the Yammer social network in Scotland through our Glow intranet (Microsoft 365). I have just been made an admin. Along with other teachers I have had some really interesting chats about how to frame this learning environment for pupils. including, learning contracts linked to appropriate use and behaviour, a digital charter linked to UNCRC and focused on what children expect from digital rights, and a third model based on the 5 iRights which are distilled amd adapted from the original UNCRC. 5rightsframework.com
  3. increase scope for our digital leaders to shape the discussion about the use of these tools and how their iRights are articulated.
  4. Lastly, I realised I gave rights little consideration photographing and publishing pictures/videos of my own children (age 3&6). I share it with them and mostly we enjoy making it together, but do they really understand who the audience or what Facebook is?

The photo credit, btw, is from 2008. A school who went too far in protecting, or rather masking, identities! http://metro.co.uk/2008/03/06/pupils-given-smileys-to-beat-online-pervs-25796/

I would love to know what you think about this and what you do in your school.


The post Digital Privacy appeared first on Through The Windae.

I saw the wild geese flee⤴

from @ Through The Windae

This post started life as part of my own reflections of how better to tell stories and ‘capture’ and ‘record’ the spontaneity of outdoor learning.

On Easter weekend the family was up north staying with my folks in the wee Angus village of Edzell. On the Monday we visited St Cyrus beach and nature reserve, a serene stretch of white sands home to Peregrine Falcons and one of my favourite places in the universe. The North Esk river completes its journey and spills out into the North Sea at an estuary further along the coastline. The heavy winter rain and storms had washed a considerable amount of wood and debris down the course of the river. All along the beach was strewn an incredible array of driftwood, including railway sleepers and one fully intact round hay bale. It was a den builder’s paradise.

Within seconds I watched my two children burst open with spontaneous creativity as they soared over the sands. In less than an hour they hand etched sand art; walked log tightropes; constructed stick canons; drawn train tracks; built dens; chased the silver tide; ran with the white horses; sculpted sand angels and told tall tales of magical stones and a new sea creature called a starfish spider. Armed with my iPhone, I ran around collecting snapshots of photos, sound and video. Their combined creativity was unrelenting and their joy extraordinarily simple. So too was their readiness to strip off, put on their dookers (swimming costumes) and run in to the freezing North Sea waves!

In the RSPB centre at the beach, someone had left a wonderful photo book which was full of similar adventures and creations made on the beach.

Later, as I sat down with the different bits of media, I reflected on how motivational, flexible and diverse that environment (context for learning) was and how deeply it had stimulated their imagination and ingenuity. There was no effort needed to enthuse them and no learning intention to guide them. In less than an hour they had covered a multitude of curriculum areas, unhinged from any sense of accountability or fear of failure. Both my kids were completely lost in the world(s) they had created. How often does that happen in the classroom? Or even in their house?! And I emphasise the word ‘created’ as in creativity. OK, you may not think it can be systematically taught or assessed but it definitely needs space to breathe.

As I started editing the footage it began to feel more like a poem, a visual collage of thoughts, sand and wind. I edited it on iMovie but none of the free music really fitted. It just didn’t feel right. Three days later it was still unfinished. Then I found myself humming a favourite folk song of mine – The Norlan Wind by the Angus folk singer Jim Reid – an adaption of a poem, The Wild Geese, by Violet Jacob. The poem is a wistful conversation between the poet (self exiled from home) and the North Wind, carrying tales and descriptions of the northern lands that the poet is dearly missing. And the melody is beautiful melancholy. I ending up using a version which is a collaboration between the Scottish bands Frightened Rabbit and Lau. It fitted perfectly. For my narrative, anyway. I think if my kids had chosen then they would have probably opted for the Scooby Doo or Spiderman theme tunes!


What started out as a rough sketch experiment of how to capture and evidence learning using my own kids as guinea pigs, ended up as a very personal visual poem. Just like the adventure on the sands, the most exciting learning is found in the spaces in-between what you think might (or should) happen and on the border crossing between control and spontaneity. If you dare to look and dream, that is.


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Model Linear Accelerator⤴

from @ stuckwithphysics.co.uk

Last June, I made a model particle accelerator using a plastic salad bowl. This was courtesy of a great 'cook-along' online CPD via Google Hangouts hosted by a fellow IOP Network Coordinator, Dan Cottle (@blendedlearner). Dan's video can be seen here - https://www.youtube.com/watch?v=4yU7rzgrg6A

This tweet from @ArdAcadPhysics shows the accelerator in action -

After building my own I was left with a huge surplus of aluminium tape, graphite paint and polystyrene balls, so i decided to run some CPD sessions to build it with other physics teachers at my own IOP CPD events.

The last of these sessions was at the ASE Scotland Conference in Aberdeen at the beginning of March. At my session one of the attendees asked it it would be possible to make a linear accelerator along the same lines. At the time the thought hadn't occurred to me, but I had a bit of a think about it over the following weeks until I found a bit of time (and the need to try it out with my own Higher physics class).

Using a bit of guttering my technician had in the stores and a lot of my surplus aluminium tape (I still have half a roll), my colleague Kenny Bell (@ArdAcadPhysics), through a process of trial and error managed to put together a working model of a linear accelerator.

Like the salad bowl accelerator this uses alternate strips of aluminium tape connected to a Van De Graaf generator, one side to the negative dome, the other side to the earth terminal.


A thin strip of aluminium tape was run along each edge of the guttering to provide common 'rail' connections form each of the terminals on the Van de Graaf. The dome is connected to the side furthest from the camera in the image above. This inturn connects to the end from which the polystyrene balls start their acceleration, which is capped and has aluminium tape over the end cap and the base of the gutter. (Care was taken to avoid having the tape touch the earth rail, which would cause a short circuit.)


IMAG0845  IMAG0846

Alternate strips of aluminium tape were connected to each of the edge rails to give alternately negatively charged (connected to the dome) and neutral (earth) electrodes. Initially electrodes of different widths were tried, but this arrangement was unsuccessful.


With the connections made, a polystyrene ball coated in conductive graphite paint was introduced at the capped end of the accelerator and the Van de Graaf generator was switched on.

A bit of tinkering was required to get the ball to accelerate along the warped guttering - achieved mainly by clamping it down to the desk. Further tinkering allowed it to be used to compare the acceleration of larger polystyrene ball with the smaller ones.

More discussion lead to the idea of using the linear accelerator to inject particles into the circular accelerator. Again, Kenny Bell offered invaluable assistance in achieving this.

If you want to use my example as a start point to build your own, please feel free to do so. if you have any questions, please get in touch via the comments below, or tweet @PhysicsDrew.

To Kill A Mockingbird⤴


Reading To Kill A Mockingbird as a teenager was a seminal moment and awakening for me as a young man. It was the book that helped bridge the gap between teen and adult fiction. I was still pulp reading the likes of James Herbert and Stephen King but discovering Harper Lee led me to discover new authors like John Steinbeck, Jack Kerouac, James Joyce and Alisdair Gray.

The tension and segregation of the American south depicted in To Kill A Mockingbird was completely alien to me, partly because I grew up in a predominately white corner of rural Scotland. But I recognised the central characters of Jem, Scout, Atticus and Boo Radley straight away. The emotions of Jem and Scout were part me and part those of my friends. Bright, adventurous and easily misled. I could see Atticus in my own dad. Kind, fair, respected by his community and someone who also had a hidden talent for sharp shooting from his army days.

Boo Radley lived on my street too. There were about 3 or 4 neighbours who had older children who had either never left home or had returned home as uni dropouts or with mental health issues. They always seemed to remain mysteriously hidden and I would only see them during personal missions like Scout Bob-A-Job weeks or hear secondhand about their tales from my folks. My favourite being the story of the minister’s son (from the ubiquitous spooky Manse next door) forming a relationship with the reclusive/dropout daughter of the house across the road. They were both in their twenties and one day decided to build a raft and adventure down the local river. The story goes that they were nearly drowned and then banned from any further contact with each other.

By the time I began my 5th year, and was studying for my Highers, I must have read To Kill A Mockingbird 3 or 4 times. I had watched the classic Gregory Peck movie and seen the play adaption in Aberdeen. English and History were my favourite subjects. I was lucky to have had the same teacher for the first 4 years of secondary school, the inspirational Mrs S. But in my 5th year I suddenly had a new teacher, and we were at loggerheads with each other from day one.

Ma C was unashamedly Conservative. She enjoyed fox hunting, sent her children to a private school and claimed there was no word in the English language she did not know (she was right too, I don’t remember ever catching her out). And she seemed to hate me. After years of consistent As and A+s I was suddenly getting constant Cs for everything.  I also used to love writing short stories but suddenly they were deemed to be universally pish. She even ‘gifted’ me a Mills and Boon book in front of the class as feedback to a story I had crafted about teenage misery and unrequited love. I read the story recently. It’s admittedly dire and bloated with verbosity and purple prose. But it’s also a cry for help. At the time I was blighted by chronic acne and suffered from intensely low self esteem. She just made it worse. I hated English, I could no longer ‘do it’ and I hated her.

But when Ma C announced that the next class text was going to be To Kill A Mockingbird and that, despite teaching it for many years, it remained her favourite book – I felt a surge of optimism. At last we had something in common. And, for a while, everything changed. I was different to her and she was different to me. I knew the novel inside out and she could tell. But I was always careful not to show off or steal her thunder (as was her teaching style).


One Monday she came into class brandishing a copy of a Sunday supplement. It was a piece about the reclusive Harper Lee in which it revealed that the author was gay. Ma C announced to the class that because of this she would find it difficult, nay impossible, to continue teaching us the book. I honestly don’t remember how exactly I reacted in that moment but I stoked residual anger and hatred towards her for many years after.

In the exam prelim I was awarded straight Cs apart from the A for my essay on To Kill A Mockingbird. It was marked by a different teacher. And in the final exam I was awarded an A. I know my adult self can calmly reason how grades are not ‘all that’ but THAT one REALLY mattered.

“You never really understand a person until you consider things from his point of view. Until you climb inside of his skin and walk around in it.”

To be honest, my teenage self was equally capable of being cocky and arrogant but I am no longer angry with Ma C. I pity her if anything. I realise now that she was afraid, just like the poor white folks who were afraid of Tom Robinson. She was afraid of the unknown. I think as a society and as a profession we’ve come a long way since then. I hope I’m not wrong.

The influence of Harper Lee has accompanied me throughout my life. At university my history degree focused on modern history, slavery and colonialism. My dissertation was on the Rev. Dr. Martin Luther King. As a teacher I have always been passionate about pupil participation, social justice, citizenship education, critical thinking and questioning. And celebrating diversity.

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Tell Me Questions⤴


One of my ‘go to’ thinking skills and discussion tools is a PPSS grid.

Puzzles, Patterns, Similarities and Surprises.

It is adapted from ‘Tell Me’, the seminal book about reading and book talk written by Aidan Chambers. The original analysis grid has Likes, Dislikes, Puzzles and Patterns.

I find it a simple yet powerful way in engaging the pupils in dialogue about books, short films, writing, self / peer assessment and why they pushed Jamie into the plant pot at lunchtime. Anything at all, really.

What puzzled you about the… ? (what do you not get?)
What patterns did you notice… ? (connections between characters, setting, music, colours, camera shots, phrases, themes)
What similarities can you find… ? (other books, films, animations, TV programmes, computer games, real life experiences)
What surprised you… ? (What happened that you were not expecting?)

The Tell Me approach extends these basic question to general questions and then special questions. There is a good one page summary here.

But I prefer and find it hard to leave the simplicity of the 4 part grid, which you or the pupils can alter and adapt, depending on the focus of the lesson and the discussion.

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