Slide Rule Workshop
#MathsConf26 10th July
UKMT Summer School 29th July
& 3rd August 2021

The curtain rising on ‘Spot the Difference’

I have been attending Maths Conferences for a number of years and benefitted greatly from the shared knowledge from other Maths enthusiasts.  I was keen to attend a workshop about the slide rule but there were none on the conference programmes.  In the unique circumstances of online conferences and the tweet by Complete Maths, asking ‘have you got a passion for Maths?’ I decided now was my opportunity to share the knowledge I had discovered on the slide rule. 

I started researching slide rules in early 2020 but due to the pandemic it was put on hold whilst I focussed on ensuring the best possible online tutoring for my students.  MathsConf26 came at an ideal time being at the end of the academic year after most of my students had completed their assessments.  I considered all the reasons why not to submit a proposal.

Meanwhile drafting a plan, this included a page on my website detailing the outline of my presentation.   I submitted a proposal & it  was accepted on 28th May. 

I had just over a month to prepare & was keen to get started on producing a workshop that was interactive and colourful.  As I prepared I had so many ‘light bulb’ revelations that lent itself to a workshop title of ‘The Highlights of The Slide Rule’.  I am certainly not an expert on this humble device but it was these highlights that I was keen to share.  There were many moments in the preparation of this workshop when my stomach literally turned over, as I asked myself how or why I thought I could explain anything to do with the slide rule.

My favourite memories & what I learnt
I love learning new technology and had wondered how it worked for conference presentation.  Check out this set up;

Mission control

It had quickly dawned on me, to present online, an extra monitor is desirable.  I ordered the cheapest I could find which arrived the day before the ‘dry run’.  The set up above includes; a monitor for the delegate view, a laptop for presenter view (to read your notes), a tablet to keep an eye on the delegate chat and a mobile phone to liaise with the conference hosts.  If you can zoom in on the mobile phone, there is some great supportive advice from Atul Rana on ‘pre-flight’ checks; make sure your Zoom screen share works well, flick through your presentation to make sure everything is where it should be.  I will add, because we had a power cut the day before the conference, get familiar with how to use ‘hotspot’ this is a great back up if there is a power failure.  I also had to put a post-it on our grill, ‘Do Not Use’, as it had been throwing the power off!  So apart from the presentation content, the whole technology side was quite daunting.  However, it was well worth getting the hang of it for a smooth experience for delegates & myself.  The tablet to monitor the chat was particularly useful to harness the engagement.  The conference was live streamed with presenters logging onto Zoom, this meant that there was only interaction on a separate webpage via chat. 

Engagement with delegates
From the outset I was keen to get as much engagement as possible.  I made use of the polls for two activities. One to establish the level of knowledge of my audience and one to gain results from a ‘Spot the difference’ between two slide rules.  I really enjoyed doing these as I was able to tailor my talk accordingly.  It turned out 57% of the audience had no knowledge of the slide rule and none claimed to be experts, Phew!  For ‘Spot the difference’ it was good for delegates to be involved and for them to see how they did using the poll.  It was also great to get posts via social media especially seeing the homemade slide rule, how else would I know that I wasn’t just talking to myself.  Thank you @mrsdenyer and @HudsonMaths.

From @mrsdenyer showing the slide rule timeline
From @HudsonMaths showing the homemade paper slide rule

There were some lovely comments in the chat, here are just a few;
   ‘It would be great to have a generation of Mathematicians who know how to be independent of technology’ Melanie Webb
   ‘Wish I still had my old slide rule! Think they are magic & something that could really inspire fascination for maths in students’ Melanie Webb
   ‘Good for teaching the importance of being able to read scale divisions!’ Dawn Denyer
    ‘If you are using Jenny’s AMAZING slide rule on the website…’ Tom Valsler
    ‘It’s working! I like it’ with reference to the homemade slide rule.  Corina Murg
     ‘How COOL is that!!’ reference to the online slide rule mirroring my grandfather’s that I used throughout the presentation.  Nikki Rohlfing
Tom Valsler, the Complete Maths host was an invaluable support, thank you.

Working with my son
Whilst researching slide rules I found many virtual ones online but none that were similar to the one I was using, being a Tamaya from Japan.  I approached my son, a software engineer, to see if he could make one for me.  I was impressed when he produced it just days before the conference.  We had to tweek the pictures for accuracy but it worked well on the day.  You can check it out here.

So MathsConf26 passed without incident and as well as I could have hoped.  As a consequence a fellow presenter and director of the UKMT virtual summer school 2021, Sue Cubbon, invited me to share the workshop with their summer students.

UKMT Virtual Summer School 2021, @UKMaths
The technology for the UKMT summer school was slightly different, this time all the students would be on the same Zoom call.  A better sense for me that an audience was definitely present. 

Set up for UKMT

This time the tablet was used to log on to Zoom twice, once for sharing the presentation and another to monitor the chat.   Once again the engagement with the students was extremely useful.  A higher proportion of around 70% had no knowledge of the slide rule.  The results for ‘Spot the difference’ are below, well done week 2!

There were some challenging questions from delegates & students and it really stretched my thinking.  Here are a few;

  1. ‘How do you find the trig values for angles in radians?’
  2. ‘Why did you use base 2 on the homemade slide rule?’
  3. ‘Why is base 10 used?’
  4. ‘Can you change a value to the log of any base using the slide rule?’


  1. Convert radians to degrees first.  Some slide rules have a gauge mark, p for this.
  2. You could use any base, I chose 2 because the numbers got less big less quickly.
  3. Using base 10 is easier as we count in tens.
  4. Yes, find it in base 10 on the slide rule and convert using the formula, see the detailed example below.

All in all, a great summer for the slide rule and a great learning experience for me.  As so often is quoted ‘you never know how well you understand something until you try explaining it to others.’  I’m not sure how well I understand the slide rule, I know it a lot better than I did and will continue to do so.
My best bit of feedback
  @HeavyMetalMaths ‘Very interesting, very slick the whole show’.  (Love how cool that sounds especially from Heavy Metal Maths).
Thanks to so many family, friends and colleagues that worked with me and helped me prepare this presentation.  I caught up with neighbours, a pilot and two Cambridge Maths graduates during my research.  Thank you to Complete Maths and the UKMT for giving me the opportunity.
After it all I needed plenty of cake which fortunately I had planned including a prototype!

Slide Rule cake using the powers of 2.

If there are any errors, omissions or misrepresentations, please let me know at [email protected]

Slide Rule Workshop

One thought on “Slide Rule Workshop

  • August 23, 2021 at 7:13 pm

    What a lovely, personal and interesting article to read! So engaging and also wonderful to hear how your family’s input helped- how special to have your grandfather’s slide rule. Bravo also on the number of screen navigations you must have made. Wow!

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