Andrew Stacey
@mathforge.org
Mathematician: formerly academic (differential topology), currently educational (Head of Department in a UK secondary school).
Side interests in Maths & Programming & Art.
Website: https://loopspace.mathforge.org
Side interests in Maths & Programming & Art.
Website: https://loopspace.mathforge.org
New visual aid for algebraic topology just dropped.
Connected#Sum #mathsky #UKMathsChat #HoagieHomies
Connected#Sum #mathsky #UKMathsChat #HoagieHomies
Porter’s Perfection set heavy clusters of fruit and in the early weeks after bloom the stems and base of the hypanthium of fruitlets that are close together can physically fuse The resulting mature apple is therefore a compound apple with a lobulated shape due to unequal growth of the fused parts
November 27, 2025 at 7:03 AM
New visual aid for algebraic topology just dropped.
Connected#Sum #mathsky #UKMathsChat #HoagieHomies
Connected#Sum #mathsky #UKMathsChat #HoagieHomies
Reposted by Andrew Stacey
I think it's time to post this again (since the thresholds have been frozen).
www.geogebra.org/m/p97htgc3
[please note this for INCOME TAX only]
www.geogebra.org/m/p97htgc3
[please note this for INCOME TAX only]
It's almost a new tax year. Here's my visualisation of how income tax works (or did in 2023-24).
Explainer vid: youtu.be/zXJCyffu8Og
Interactive version: www.geogebra.org/m/p97htgc3
Explainer vid: youtu.be/zXJCyffu8Og
Interactive version: www.geogebra.org/m/p97htgc3
November 26, 2025 at 4:18 PM
I think it's time to post this again (since the thresholds have been frozen).
www.geogebra.org/m/p97htgc3
[please note this for INCOME TAX only]
www.geogebra.org/m/p97htgc3
[please note this for INCOME TAX only]
In #MathsToday a student asked about integrating 1/sqrt(1+x²). We haven't covered hyperbolics yet, but that got me pondering - there is a non-hyperbolic answer, so is there a route to it that doesn't go via hyperbolics?
#UKMathsChat #ALevelMaths #ITeachMaths
#UKMathsChat #ALevelMaths #ITeachMaths
November 26, 2025 at 3:43 PM
In #MathsToday a student asked about integrating 1/sqrt(1+x²). We haven't covered hyperbolics yet, but that got me pondering - there is a non-hyperbolic answer, so is there a route to it that doesn't go via hyperbolics?
#UKMathsChat #ALevelMaths #ITeachMaths
#UKMathsChat #ALevelMaths #ITeachMaths
Reposted by Andrew Stacey
I enjoyed doing this question with Y7 #MathsToday. I need to remember to revisit this with Y8 when they start standard form - it’s exactly the way I want them to be thinking about it.
November 25, 2025 at 4:56 PM
I enjoyed doing this question with Y7 #MathsToday. I need to remember to revisit this with Y8 when they start standard form - it’s exactly the way I want them to be thinking about it.
Recommendation request: a good first (undergraduate) text in group theory.
Thanks!
#mathsky #ITeachMaths #UKMathsChat #HoagieHomies
Thanks!
#mathsky #ITeachMaths #UKMathsChat #HoagieHomies
November 23, 2025 at 9:29 PM
Recommendation request: a good first (undergraduate) text in group theory.
Thanks!
#mathsky #ITeachMaths #UKMathsChat #HoagieHomies
Thanks!
#mathsky #ITeachMaths #UKMathsChat #HoagieHomies
Reposted by Andrew Stacey
what is ironing if not differential topology
November 22, 2025 at 11:22 PM
what is ironing if not differential topology
Reposted by Andrew Stacey
VERY IMPORTANT IDEA: the next academic conference I attend should have a "tea exchange" where we all just bring a bunch of our favorite tea, try each others, and then everyone leaves with some new tea that they liked.
This is unironically a 10/10 networking idea and I'm not too humble to admit it.
This is unironically a 10/10 networking idea and I'm not too humble to admit it.
November 21, 2025 at 3:19 PM
VERY IMPORTANT IDEA: the next academic conference I attend should have a "tea exchange" where we all just bring a bunch of our favorite tea, try each others, and then everyone leaves with some new tea that they liked.
This is unironically a 10/10 networking idea and I'm not too humble to admit it.
This is unironically a 10/10 networking idea and I'm not too humble to admit it.
Reposted by Andrew Stacey
These new papers on the 'dga of planar loops' look very fun: arxiv.org/abs/2511.15653 🧮
November 21, 2025 at 3:58 AM
These new papers on the 'dga of planar loops' look very fun: arxiv.org/abs/2511.15653 🧮
Reposted by Andrew Stacey
I used this yesterday with Y7. The number line helped them get their heads around the idea that there is one more "jump" than blanks to fill.
#MathsToday
#MathsToday
November 20, 2025 at 10:12 AM
I used this yesterday with Y7. The number line helped them get their heads around the idea that there is one more "jump" than blanks to fill.
#MathsToday
#MathsToday
This is awesome.
I'm a particular fan of it being grouped by *final* grade. I think that is a really crucial aspect of what is presented to students. Rather than saying what will happen to them, describe possible trajectories and ask "what would you like to happen? What will *you* do?"
I'm a particular fan of it being grouped by *final* grade. I think that is a really crucial aspect of what is presented to students. Rather than saying what will happen to them, describe possible trajectories and ask "what would you like to happen? What will *you* do?"
In lieu of grade boundaries, I showed them these histograms, of previous students grouped by the grade they ended up with. Took a bit of explaining, but I hope it helped them see what they were on track for, without me having to give them an explicit grade. #MathsToday
November 19, 2025 at 9:59 PM
This is awesome.
I'm a particular fan of it being grouped by *final* grade. I think that is a really crucial aspect of what is presented to students. Rather than saying what will happen to them, describe possible trajectories and ask "what would you like to happen? What will *you* do?"
I'm a particular fan of it being grouped by *final* grade. I think that is a really crucial aspect of what is presented to students. Rather than saying what will happen to them, describe possible trajectories and ask "what would you like to happen? What will *you* do?"
Reposted by Andrew Stacey
I'm looking for a thing but my web searching skills are failing me...
I was in an online training thing once, and the presenter shared a link to an online map. This map allowed everyone in the meeting to click on the map to indicate where they were in the real world, and then the presenter was […]
I was in an online training thing once, and the presenter shared a link to an online map. This map allowed everyone in the meeting to click on the map to indicate where they were in the real world, and then the presenter was […]
Original post on mathstodon.xyz
mathstodon.xyz
November 18, 2025 at 5:33 PM
I'm looking for a thing but my web searching skills are failing me...
I was in an online training thing once, and the presenter shared a link to an online map. This map allowed everyone in the meeting to click on the map to indicate where they were in the real world, and then the presenter was […]
I was in an online training thing once, and the presenter shared a link to an online map. This map allowed everyone in the meeting to click on the map to indicate where they were in the real world, and then the presenter was […]
Reposted by Andrew Stacey
❤️ Love this ❤️
@mathforge.org has done what I’ve never been organised enough to do myself, and catalogued every #geometrypuzzle I’ve ever posted on social media. It looks amazing!
@mathforge.org has done what I’ve never been organised enough to do myself, and catalogued every #geometrypuzzle I’ve ever posted on social media. It looks amazing!
November 17, 2025 at 6:33 AM
❤️ Love this ❤️
@mathforge.org has done what I’ve never been organised enough to do myself, and catalogued every #geometrypuzzle I’ve ever posted on social media. It looks amazing!
@mathforge.org has done what I’ve never been organised enough to do myself, and catalogued every #geometrypuzzle I’ve ever posted on social media. It looks amazing!
Reposted by Andrew Stacey
Coffee will fix it.
November 17, 2025 at 6:02 PM
Coffee will fix it.
Reposted by Andrew Stacey
🦂🚨🦂 New Chalkdust alert! 🦂🚨🦂
DNA origami, tracks and an interview with El Nombre feature in our AW25 issue! Plus all your favourite puzzles & columns.
Read the entire new issue now at
chalkdustmagazine.com
DNA origami, tracks and an interview with El Nombre feature in our AW25 issue! Plus all your favourite puzzles & columns.
Read the entire new issue now at
chalkdustmagazine.com
Chalkdust: Read Issue 22 now
A magazine for the mathematically curious. Issue 22 now available: DNA origami, tracks and an interview with El Nombre feature in our AW25 issue! Plus all your favourite puzzles & columns.
chalkdustmagazine.com
November 17, 2025 at 11:24 AM
🦂🚨🦂 New Chalkdust alert! 🦂🚨🦂
DNA origami, tracks and an interview with El Nombre feature in our AW25 issue! Plus all your favourite puzzles & columns.
Read the entire new issue now at
chalkdustmagazine.com
DNA origami, tracks and an interview with El Nombre feature in our AW25 issue! Plus all your favourite puzzles & columns.
Read the entire new issue now at
chalkdustmagazine.com
Reposted by Andrew Stacey
An interaction at yesterday's launch of #MathsWeekEngland at the new MathsWorld venue near London's Bankside.
Mum with child: "What do you call the type of maths that's here at MathsWorld?"
Me: "It's officially called 'fun and interesting' maths"
Mum: "Ooh, we love this sort of maths"
Mum with child: "What do you call the type of maths that's here at MathsWorld?"
Me: "It's officially called 'fun and interesting' maths"
Mum: "Ooh, we love this sort of maths"
November 16, 2025 at 11:00 PM
An interaction at yesterday's launch of #MathsWeekEngland at the new MathsWorld venue near London's Bankside.
Mum with child: "What do you call the type of maths that's here at MathsWorld?"
Me: "It's officially called 'fun and interesting' maths"
Mum: "Ooh, we love this sort of maths"
Mum with child: "What do you call the type of maths that's here at MathsWorld?"
Me: "It's officially called 'fun and interesting' maths"
Mum: "Ooh, we love this sort of maths"
Sunday night seems the right time to post a gallery of (I hope!) every one of Catriona's geometry puzzles.
notes.mathforge.org/notes/publis...
Give it a moment to load ... there's a *lot* of them!
#GeometryPuzzles #UKMathsChat #mathsky
notes.mathforge.org/notes/publis...
Give it a moment to load ... there's a *lot* of them!
#GeometryPuzzles #UKMathsChat #mathsky
Puzzle Gallery in Notes
notes.mathforge.org
November 16, 2025 at 6:24 PM
Sunday night seems the right time to post a gallery of (I hope!) every one of Catriona's geometry puzzles.
notes.mathforge.org/notes/publis...
Give it a moment to load ... there's a *lot* of them!
#GeometryPuzzles #UKMathsChat #mathsky
notes.mathforge.org/notes/publis...
Give it a moment to load ... there's a *lot* of them!
#GeometryPuzzles #UKMathsChat #mathsky
Idly perusing the bookcase (sorted by colour, of course) and noticing a few things.
Most books by a single author: Terry Pratchett (no contest)
#Books #IdleMusings #BookShelfOddities
Most books by a single author: Terry Pratchett (no contest)
#Books #IdleMusings #BookShelfOddities
November 16, 2025 at 6:21 PM
Idly perusing the bookcase (sorted by colour, of course) and noticing a few things.
Most books by a single author: Terry Pratchett (no contest)
#Books #IdleMusings #BookShelfOddities
Most books by a single author: Terry Pratchett (no contest)
#Books #IdleMusings #BookShelfOddities
Reposted by Andrew Stacey
November 16, 2025 at 12:34 AM
Just started 2nd order ODEs, decided to start with coupled 1st order.
Rationale:
1. Modelling. Start with y'=ky modelling a single population, bring in a second with interaction.
2. Exponential. Solution to single pop is exp, so reasonable to try for double.
#ALevelMaths #UKMathsChat #MathsToday
Rationale:
1. Modelling. Start with y'=ky modelling a single population, bring in a second with interaction.
2. Exponential. Solution to single pop is exp, so reasonable to try for double.
#ALevelMaths #UKMathsChat #MathsToday
November 12, 2025 at 8:11 PM
Just started 2nd order ODEs, decided to start with coupled 1st order.
Rationale:
1. Modelling. Start with y'=ky modelling a single population, bring in a second with interaction.
2. Exponential. Solution to single pop is exp, so reasonable to try for double.
#ALevelMaths #UKMathsChat #MathsToday
Rationale:
1. Modelling. Start with y'=ky modelling a single population, bring in a second with interaction.
2. Exponential. Solution to single pop is exp, so reasonable to try for double.
#ALevelMaths #UKMathsChat #MathsToday
Did not realise that Bees and Bombs had made the leap to BlueSky!
#UKMathsChat #mathsky #HoagieHomies
#UKMathsChat #mathsky #HoagieHomies
November 11, 2025 at 7:14 PM
Did not realise that Bees and Bombs had made the leap to BlueSky!
#UKMathsChat #mathsky #HoagieHomies
#UKMathsChat #mathsky #HoagieHomies
Reposted by Andrew Stacey
Giant cardioid: version 2.5. Version 1.0 was made using Pex tubing and grommet tape. Version 2.0 was made from laser-cut pieces. The wood was too fragile, and it broke during construction. In version 2.5, I made the pieces wider and I used thicker wood. Success, I'd say! The diameter is about 5 ft.
November 9, 2025 at 4:34 PM
Giant cardioid: version 2.5. Version 1.0 was made using Pex tubing and grommet tape. Version 2.0 was made from laser-cut pieces. The wood was too fragile, and it broke during construction. In version 2.5, I made the pieces wider and I used thicker wood. Success, I'd say! The diameter is about 5 ft.
Reposted by Andrew Stacey
Interested in studying statistics @ox.ac.uk? Join us for our Postgraduate Open Day and find out more about the courses we offer.
📅 Wednesday 19 November 2025
⌚ From 1pm
📍 In-person and online
📃 Please register by Monday 17 November at: forms.office.com/r/Q6HxgLR16C
#postgrad #openday
📅 Wednesday 19 November 2025
⌚ From 1pm
📍 In-person and online
📃 Please register by Monday 17 November at: forms.office.com/r/Q6HxgLR16C
#postgrad #openday
November 5, 2025 at 4:37 PM
Interested in studying statistics @ox.ac.uk? Join us for our Postgraduate Open Day and find out more about the courses we offer.
📅 Wednesday 19 November 2025
⌚ From 1pm
📍 In-person and online
📃 Please register by Monday 17 November at: forms.office.com/r/Q6HxgLR16C
#postgrad #openday
📅 Wednesday 19 November 2025
⌚ From 1pm
📍 In-person and online
📃 Please register by Monday 17 November at: forms.office.com/r/Q6HxgLR16C
#postgrad #openday
Reposted by Andrew Stacey
We're hoping to avoid any interview horror stories this Halloween 👻 We've teamed up with @brasenoseoxford.bsky.social to host 11 online interview workshops 3–17 November for anyone applying to @cam.ac.uk or @ox.ac.uk for undergraduate courses. Find out more & sign up:
Applicant webinars 2025
St Catharine's College is collaborating with Brasenose College (University of Oxford) to deliver a series of free webinars in 2025 for students thinking of applying to the Universities of Oxford or Cambridge in 2026. Outreach staff will be delivering sessions with Oxbridge academics and students to:
caths.cam.ac.uk
October 31, 2025 at 9:30 AM
We're hoping to avoid any interview horror stories this Halloween 👻 We've teamed up with @brasenoseoxford.bsky.social to host 11 online interview workshops 3–17 November for anyone applying to @cam.ac.uk or @ox.ac.uk for undergraduate courses. Find out more & sign up:
Reposted by Andrew Stacey
Recently I was playing with the Square-Sums Puzzle (as explored previously by @standupmaths.bsky.social on Numberphile) and realised it would be fun for schools. So here is a FREE teacher resource: think-maths.co.uk/square-sums (and enjoy its use being modelled by my in-house mathematician below).
October 31, 2025 at 4:21 PM
Recently I was playing with the Square-Sums Puzzle (as explored previously by @standupmaths.bsky.social on Numberphile) and realised it would be fun for schools. So here is a FREE teacher resource: think-maths.co.uk/square-sums (and enjoy its use being modelled by my in-house mathematician below).
I even found a copy in that intellectual backwater that is Cambridge .
@teakayb.mathstodon.xyz.ap.brid.gy
@teakayb.mathstodon.xyz.ap.brid.gy
October 26, 2025 at 8:33 PM
I even found a copy in that intellectual backwater that is Cambridge .
@teakayb.mathstodon.xyz.ap.brid.gy
@teakayb.mathstodon.xyz.ap.brid.gy