Justin Lanier
@jlanier.bsky.social
Reposted by Justin Lanier
Moon Duchin on the ‘Mathematical Quagmire’ of Gerrymandering
www.nytimes.com
November 3, 2025 at 12:43 PM
If you teach Year 6 maths in the UK and you'd be willing to Zoom chat briefly with a pre-service teacher in the US for a class project, let me know? Thanks!
November 2, 2025 at 8:55 PM
If you teach Year 6 maths in the UK and you'd be willing to Zoom chat briefly with a pre-service teacher in the US for a class project, let me know? Thanks!
Reposted by Justin Lanier
I presented on this problem today!
You can find the slides here:
docs.google.com/presentation...
I don't use speaker notes (just vibes) but I think a recorded version exists and I'll try to link to it if/when I can.
cc #iTeachMath ♾️ bcc #MathSky 🧮
You can find the slides here:
docs.google.com/presentation...
I don't use speaker notes (just vibes) but I think a recorded version exists and I'll try to link to it if/when I can.
cc #iTeachMath ♾️ bcc #MathSky 🧮
August 8, 2025 at 11:23 PM
I presented on this problem today!
You can find the slides here:
docs.google.com/presentation...
I don't use speaker notes (just vibes) but I think a recorded version exists and I'll try to link to it if/when I can.
cc #iTeachMath ♾️ bcc #MathSky 🧮
You can find the slides here:
docs.google.com/presentation...
I don't use speaker notes (just vibes) but I think a recorded version exists and I'll try to link to it if/when I can.
cc #iTeachMath ♾️ bcc #MathSky 🧮
Reposted by Justin Lanier
Yesterday I spent a fascinating morning talking maths with a group of GPs. All professions require some level of numeracy, but doctors face particular challenges when communicating mathematical ideas.
I've written up a short blog: robeastaway.com/blog/gp-maths
I've written up a short blog: robeastaway.com/blog/gp-maths
July 31, 2025 at 7:50 PM
Yesterday I spent a fascinating morning talking maths with a group of GPs. All professions require some level of numeracy, but doctors face particular challenges when communicating mathematical ideas.
I've written up a short blog: robeastaway.com/blog/gp-maths
I've written up a short blog: robeastaway.com/blog/gp-maths
Reposted by Justin Lanier
Applications are now open for our International Visitor Program, open to #mathematicians to visit Aus 🐨 between July '26-'June 27, or March '26-June -27 (Aus/NZ citizens)
📅 Apply by Aug 1, info:
mathematical-research-institute.sydney.edu.au/internationa...
Please share with your networks 🔁 #MathSky
📅 Apply by Aug 1, info:
mathematical-research-institute.sydney.edu.au/internationa...
Please share with your networks 🔁 #MathSky
International Visitor Program - Sydney Mathematical Research Institute
IVP August 2023 applications are due 8 August 2023, for July 2024–June 2025 visits (general applicants) & March 2024–June 2025 for Australian citizens/PR & NZ citizens.
mathematical-research-institute.sydney.edu.au
July 3, 2025 at 12:06 AM
Applications are now open for our International Visitor Program, open to #mathematicians to visit Aus 🐨 between July '26-'June 27, or March '26-June -27 (Aus/NZ citizens)
📅 Apply by Aug 1, info:
mathematical-research-institute.sydney.edu.au/internationa...
Please share with your networks 🔁 #MathSky
📅 Apply by Aug 1, info:
mathematical-research-institute.sydney.edu.au/internationa...
Please share with your networks 🔁 #MathSky
Reposted by Justin Lanier
“21st century mathematics”: a free month-long online enrichment program for math teachers.
Info + register: bit.ly/21math2025
Video part 1:
Info + register: bit.ly/21math2025
Video part 1:
April 23, 2025 at 1:10 PM
“21st century mathematics”: a free month-long online enrichment program for math teachers.
Info + register: bit.ly/21math2025
Video part 1:
Info + register: bit.ly/21math2025
Video part 1:
TIL that we narrowly missing lugging around not only the monikers "imaginary", "negative", "complex", and "irrational" for numbers, but also "fictitious limits". Real glad for that. 😅
from MacTutor's "The real numbers: Stevin to Hilbert"
from MacTutor's "The real numbers: Stevin to Hilbert"
June 27, 2025 at 4:33 AM
TIL that we narrowly missing lugging around not only the monikers "imaginary", "negative", "complex", and "irrational" for numbers, but also "fictitious limits". Real glad for that. 😅
from MacTutor's "The real numbers: Stevin to Hilbert"
from MacTutor's "The real numbers: Stevin to Hilbert"
We are two weeks out from the start of "21st century mathematics", a program I run for K-12 math teachers. (Register now!) The program helps teachers connect the math they teach with some math that has been discovered in the 21st century. The program is flexible, free, & online.
June 23, 2025 at 2:00 PM
We are two weeks out from the start of "21st century mathematics", a program I run for K-12 math teachers. (Register now!) The program helps teachers connect the math they teach with some math that has been discovered in the 21st century. The program is flexible, free, & online.
Reposted by Justin Lanier
"While everyone is glad to have a much-deserved break from the routine of early mornings and late evenings, as teachers we often end the school year thinking about the things we 'just didn’t have time to cover'."
Read NCTM President @latrendak.bsky.social's full message here: nctm.link/a3H7t
Read NCTM President @latrendak.bsky.social's full message here: nctm.link/a3H7t
June 5, 2025 at 1:50 PM
"While everyone is glad to have a much-deserved break from the routine of early mornings and late evenings, as teachers we often end the school year thinking about the things we 'just didn’t have time to cover'."
Read NCTM President @latrendak.bsky.social's full message here: nctm.link/a3H7t
Read NCTM President @latrendak.bsky.social's full message here: nctm.link/a3H7t
Reposted by Justin Lanier
Have you followed along with Math On-A-Stick and wondered what it would take to make this kind of joyful, creative math happen in your locality?
Well, let's gooooooooooooooo
www.mathhappens.org/math-at-the-...
Well, let's gooooooooooooooo
www.mathhappens.org/math-at-the-...
Math at the Fair - MathHappens
Math at the Fair MathHappens Foundation is inviting applications for teams to participate in Math at the Fair, a project that aims to build playful and creative math experiences at fairs and similar e...
www.mathhappens.org
May 30, 2025 at 6:26 PM
Have you followed along with Math On-A-Stick and wondered what it would take to make this kind of joyful, creative math happen in your locality?
Well, let's gooooooooooooooo
www.mathhappens.org/math-at-the-...
Well, let's gooooooooooooooo
www.mathhappens.org/math-at-the-...
May 6, 2025 at 2:53 PM
Big day here in Australia.
May 3, 2025 at 2:23 AM
Big day here in Australia.
Reposted by Justin Lanier
Ten squares. The first example has perimeter 14. The second one has perimeter 22. Can anyone find ones with smaller or bigger perimeters? Or other examples that match these?
Intrigued? Check out "21st century mathematics", an enrichment program for teachers: justinlanier.org/21st-century...
Intrigued? Check out "21st century mathematics", an enrichment program for teachers: justinlanier.org/21st-century...
April 28, 2025 at 11:27 AM
Ten squares. The first example has perimeter 14. The second one has perimeter 22. Can anyone find ones with smaller or bigger perimeters? Or other examples that match these?
Intrigued? Check out "21st century mathematics", an enrichment program for teachers: justinlanier.org/21st-century...
Intrigued? Check out "21st century mathematics", an enrichment program for teachers: justinlanier.org/21st-century...
Ten squares. The first example has perimeter 14. The second one has perimeter 22. Can anyone find ones with smaller or bigger perimeters? Or other examples that match these?
Intrigued? Check out "21st century mathematics", an enrichment program for teachers: justinlanier.org/21st-century...
Intrigued? Check out "21st century mathematics", an enrichment program for teachers: justinlanier.org/21st-century...
April 28, 2025 at 11:27 AM
Ten squares. The first example has perimeter 14. The second one has perimeter 22. Can anyone find ones with smaller or bigger perimeters? Or other examples that match these?
Intrigued? Check out "21st century mathematics", an enrichment program for teachers: justinlanier.org/21st-century...
Intrigued? Check out "21st century mathematics", an enrichment program for teachers: justinlanier.org/21st-century...
Reposted by Justin Lanier
Are you a mathematics teacher? Would you like a taste of 21st century mathematics? See the link below to join a program for teachers run by Justin Lanier @jlanier.bsky.social —stay for as long as you like, explore with friends, & get your own insights into accessible, deep questions in math
“21st century mathematics”: a free month-long online enrichment program for math teachers.
Info + register: bit.ly/21math2025
Video part 1:
Info + register: bit.ly/21math2025
Video part 1:
April 23, 2025 at 8:49 PM
Are you a mathematics teacher? Would you like a taste of 21st century mathematics? See the link below to join a program for teachers run by Justin Lanier @jlanier.bsky.social —stay for as long as you like, explore with friends, & get your own insights into accessible, deep questions in math
“21st century mathematics”: a free month-long online enrichment program for math teachers.
Info + register: bit.ly/21math2025
Video part 1:
Info + register: bit.ly/21math2025
Video part 1:
April 23, 2025 at 1:10 PM
“21st century mathematics”: a free month-long online enrichment program for math teachers.
Info + register: bit.ly/21math2025
Video part 1:
Info + register: bit.ly/21math2025
Video part 1:
Reposted by Justin Lanier
Hi! In July I'm once again running a program for K-12 math teachers called "21st century mathematics". Its goal is to help teachers to connect math they teach with some math that has been discovered in the 21st century.
Pass it along!
Info+register:
justinlanier.org/21st-century...
Pass it along!
Info+register:
justinlanier.org/21st-century...
21st century mathematics – 2025
An online learning experience for math teachers Registration for the 2025 program is now open! Here is the registration form. Registration will continue through the start of the program in July. Al…
justinlanier.org
April 16, 2025 at 4:02 AM
Hi! In July I'm once again running a program for K-12 math teachers called "21st century mathematics". Its goal is to help teachers to connect math they teach with some math that has been discovered in the 21st century.
Pass it along!
Info+register:
justinlanier.org/21st-century...
Pass it along!
Info+register:
justinlanier.org/21st-century...
Hi! In July I'm once again running a program for K-12 math teachers called "21st century mathematics". Its goal is to help teachers to connect math they teach with some math that has been discovered in the 21st century.
Pass it along!
Info+register:
justinlanier.org/21st-century...
Pass it along!
Info+register:
justinlanier.org/21st-century...
21st century mathematics – 2025
An online learning experience for math teachers Registration for the 2025 program is now open! Here is the registration form. Registration will continue through the start of the program in July. Al…
justinlanier.org
April 16, 2025 at 4:02 AM
Hi! In July I'm once again running a program for K-12 math teachers called "21st century mathematics". Its goal is to help teachers to connect math they teach with some math that has been discovered in the 21st century.
Pass it along!
Info+register:
justinlanier.org/21st-century...
Pass it along!
Info+register:
justinlanier.org/21st-century...
"𝘉𝘳𝘪𝘯𝘨 𝘐𝘵 𝘖𝘯: 𝘐𝘯 𝘐𝘵 𝘵𝘰 𝘞𝘪𝘯 and 𝘞𝘦𝘴𝘵 𝘚𝘪𝘥𝘦 𝘚𝘵𝘰𝘳𝘺 are basically the same movie. They're romeomorphic."
April 1, 2025 at 1:02 AM
"𝘉𝘳𝘪𝘯𝘨 𝘐𝘵 𝘖𝘯: 𝘐𝘯 𝘐𝘵 𝘵𝘰 𝘞𝘪𝘯 and 𝘞𝘦𝘴𝘵 𝘚𝘪𝘥𝘦 𝘚𝘵𝘰𝘳𝘺 are basically the same movie. They're romeomorphic."
Find the derivative of f(x) = sin²(x) + cos²(x) in two different ways.
March 6, 2025 at 12:07 AM
Find the derivative of f(x) = sin²(x) + cos²(x) in two different ways.
Reposted by Justin Lanier
Here's the first page of Radical Equations; I hope it grabs your attention!
It's available from lots of independent booksellers, and it's available digitally via Kindle and Audible. (Ask your library to get a copy!)
It's available from lots of independent booksellers, and it's available digitally via Kindle and Audible. (Ask your library to get a copy!)
![CHAPTER 1
Algebra and Civil Rights?
[start of inset quotation]
In order for us as poor and oppressed people to become a part of a society that is meaningful, the system under which we now exist has to be radically changed. This means that we are going to have to learn to think in radical terms. I use the term radical in its original meaning-getting down to and understanding the root cause. It means facing a system that does not lend itself to your needs and devising means by which you change that system. That is easier said than done. But one of the things that has to be faced is, in the process of wanting to change that system, how much have we got to do to find out who we are, where we have come from and where we are going.... I am saying as you must say, too, that in order to see where we are going, we not only must remember where we have been, but we must understand where we have been.
–Ella Baker
[end of inset quotation]
The sit-ins woke me up.
Until then, my Black life was conflicted. I was a twenty-six-year-old teacher at Horace Mann, an elite private school in the Bronx, moving back and forth between the sharply contrasting worlds of Hamilton College, Harvard University, Horace Mann, and Harlem.
[the first page of Radical Equations]](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:ulooyxsddue5iug4wt6evexi/bafkreie5xq4fchvuu74oylk7bpyxpzotaifofitubxxtqzgs5r62ylsrku@jpeg)
February 1, 2025 at 11:57 PM
Here's the first page of Radical Equations; I hope it grabs your attention!
It's available from lots of independent booksellers, and it's available digitally via Kindle and Audible. (Ask your library to get a copy!)
It's available from lots of independent booksellers, and it's available digitally via Kindle and Audible. (Ask your library to get a copy!)
Advice please:
Someone registers for a program I run (through a Google Form) & gives me their email address. But when I try emailing them later, maybe it gets sent to their spam, or maybe they mistyped and I receive an error message back.
What's a good way to automate an email confirmation check?
Someone registers for a program I run (through a Google Form) & gives me their email address. But when I try emailing them later, maybe it gets sent to their spam, or maybe they mistyped and I receive an error message back.
What's a good way to automate an email confirmation check?
January 31, 2025 at 2:09 AM
Advice please:
Someone registers for a program I run (through a Google Form) & gives me their email address. But when I try emailing them later, maybe it gets sent to their spam, or maybe they mistyped and I receive an error message back.
What's a good way to automate an email confirmation check?
Someone registers for a program I run (through a Google Form) & gives me their email address. But when I try emailing them later, maybe it gets sent to their spam, or maybe they mistyped and I receive an error message back.
What's a good way to automate an email confirmation check?
Reposted by Justin Lanier
Reflecting on explorations in math place, and something called the Rosenthal Prize:
fivetwelvethirteen.substack.com/p/exploratio...
fivetwelvethirteen.substack.com/p/exploratio...
Explorations in Math Class
Quality over quantity
fivetwelvethirteen.substack.com
January 21, 2025 at 1:13 PM
Reflecting on explorations in math place, and something called the Rosenthal Prize:
fivetwelvethirteen.substack.com/p/exploratio...
fivetwelvethirteen.substack.com/p/exploratio...
Reposted by Justin Lanier
Alright, help me fill up this starter pack. Are there other current K-12 classroom teachers who want to be added, or have cutbacks reduced the math teaching community to this list of 64 (wonderful) individuals? 😂
Made a Starter Pack of *current* K-12 math classroom teachers. Let me know if you should be added (or removed).
go.bsky.app/35M7izP
go.bsky.app/35M7izP
January 16, 2025 at 2:56 AM
Alright, help me fill up this starter pack. Are there other current K-12 classroom teachers who want to be added, or have cutbacks reduced the math teaching community to this list of 64 (wonderful) individuals? 😂
Who are you cheering for tonight?
- 2024
- 2025
- I just hope it's a good game.
- 2024
- 2025
- I just hope it's a good game.
December 31, 2024 at 5:57 AM
Who are you cheering for tonight?
- 2024
- 2025
- I just hope it's a good game.
- 2024
- 2025
- I just hope it's a good game.