Julian Gilbey

Maths teacher, formerly researcher in data science and image processing, working on the BloodCounts! project; former resource designer for @UndergroundMath

[Julian Gilbey @JulianMaths]

@adamboxer1 Oh wow!

[Ihtesham Ali @ihtesham2005]

An MIT professor taught the same math course for 62 years, and the day he retired, students from every country on earth showed up online to watch him give his final lecture.

I opened the playlist at 2am and ended up watching three of them back to back.

His name is Gilbert Strang. The course is MIT 18.06 Linear Algebra.

Every machine learning engineer, every data scientist, every quant, every self-taught programmer who actually understands how AI works learned the math from this one man. Most of them never set foot on MIT's campus. They just opened a free playlist on YouTube and let him teach.

Here's the story almost nobody tells you.

Strang joined the MIT math faculty in 1962. He retired in 2023. That is 61 years of standing at the same chalkboard teaching the same subject to 18-year-olds.

The interesting part is what he did when MIT launched OpenCourseWare in 2002. Most professors were skeptical. They worried that putting their lectures online would make their classrooms irrelevant. Strang did not hesitate. He said his life's mission was to open mathematics to students everywhere. He filmed every lecture and gave it away.

The decision quietly changed how the world learns math.

For decades linear algebra was taught the wrong way. Professors started with abstract vector spaces and proofs about field axioms. Students drowned in the abstraction. Most never recovered. They walked out believing they were bad at math when they had simply been taught in an order that nobody's brain is built to absorb.

Strang inverted the entire curriculum.

He started with matrix multiplication. Something you can write down on paper. Something you can compute by hand. Something you can see. Then he showed his students that everything else in linear algebra eigenvectors, singular value decomposition, orthogonality, the four fundamental subspaces was just a different lens for understanding what the matrix was actually doing under the hood.

His rule was strict. If a student could not explain a concept using a concrete 3 by 3 example, that student did not actually understand the concept yet. The abstraction was supposed to come last, not first. The intuition was the foundation. The proofs were just confirmation that the intuition was correct.

The second thing Strang changed was the classroom itself. He said please and thank you to his students. Every single lecture. He paused mid-derivation to ask "am I OK?" to check if anyone was lost. He never used the word "obviously" or "trivially" because he knew exactly what those words do to a student who is one step behind. He treated 19-year-olds learning math for the first time the way he treated his own colleagues. With patience. With respect. With the assumption that they belonged in the room.

For 62 years.

The result is something that has never happened in the history of education. A single math professor became the default teacher of his subject for the entire planet.

Universities in India, China, Brazil, Nigeria, every country with a computer science department, started telling their own students to just watch Strang's lectures. The University of Illinois revised its linear algebra course to do almost no in-person lecturing. The reason was honest. The professor said they could not compete with the videos.

His final lecture was in May 2023.

The auditorium was packed with students who had never met him before. He walked to the chalkboard, taught for an hour, and at the end the entire room stood and applauded. He looked confused for a moment, like he genuinely did not understand why they were cheering. Then he smiled and waved them off and walked out.

His written comment under the YouTube video of that final lecture was four sentences long. He said teaching had been a wonderful life. He said he was grateful to everyone who saw the importance of linear algebra. He said the movement of teaching it well would continue because it was right.

That was it. No book promotion. No farewell speech. No legacy management.

The man whose teaching is the foundation of modern AI just thanked the audience and went home.

20 million views. Zero ego. The entire engine of the AI revolution sits on top of math that millions of people learned for free from one quiet professor in Cambridge.

The course is still on MIT OpenCourseWare. Every lecture, every problem set, every exam, every solution. Free.

The most important math course of the 21st century is sitting one click away from you. Most people will never open it.

[Julian Gilbey @JulianMaths]

@adamboxer1 Except for the fact that this is the method used by computers for calculating gcds (with various efficiency tweaks), and that lies at the heart of one of the major cryptographic protocols used for the Internet...

[The Maths Bazaar @themathsbazaar]

GENUINE fact (not a "bit"):

The date is 5^2 / 3^2 / 45^2

It is probably the last time in your lifetime where all three numbers are square (the next one being 1/1/2116)

[Rob Eastaway @robeastaway]

MATHS TEACHERS: If you’re seeking ways to add quirky ‘real world’ maths to lessons next year I’ve updated my blog index https://t.co/gvU8G90EeX . You can use it to find odd applications of (say) quadratic equations. It’s the sort of thing you might use as a lesson starter (1/3)

[Julian Gilbey @JulianMaths]

@Miss_Snuffy Congratulations on your amazing results!

[The Maths Bazaar @themathsbazaar]

Edapt do what unions don't - focus on the teachers and the policy updates that affect them, rather than the political infighting and causes unrelated to the classroom.
Save £30 on an annual membership by enrolling at https://t.co/vvclvlcSm8
@edaptuk

[Julian Gilbey @JulianMaths]

@adamboxer1 @dare_richard I would probably follow with something like "Now everyone, returning to the question of..."

[Julian Gilbey @JulianMaths]

@adamboxer1 @dare_richard But since you have called out again, you now have a consequence." 2/2

[David Didau @DavidDidau]

On the process of building culture in school and the problem with impatience. Link in reply

[Julian Gilbey @JulianMaths]

@adamboxer1 I sense that his use of the word "fun" here doesn't mean "colouring in silly pictures" or the like, but rather having fun playing with ideas, being in an open state for learning something - the second half about "the pleasure of finding things out" illuminates the first half.

[Julian Gilbey @JulianMaths]

@rob_fletcher_ @adamboxer1 More significantly, the time wasted doing this could be used for far better purposes such as lesson PREPARATION (TLAC Technique #1)

[David Spiegelhalter @d_spiegel]

In uncertain times....

[Julian Gilbey @JulianMaths]

It was a delight to visit @totteridgeacad yesterday and to imbibe the atmosphere. Amazingly focused, purposeful and calm lessons, engaged students, and enthusiastic staff. Thanks for the warm welcome, and I look forward to incorporating some of what I learnt in the near future!

[Pritesh Raichura @Mr_Raichura]

Super blog from @stoneman_claire.

Techniques are tools. Alone, they don’t make a teacher better. Excellent CPD focuses on giving teachers a coherent *strategy* in how & when to deploy techniques. Teachers must understand the ‘why’.

[Julian Gilbey @JulianMaths]

@TeachBeech2 Congratulations! If you haven't come across them, @mrbartonmaths has an excellent podcast (>200 episodes now) with lots of them being focused specifically on secondary maths. Ollie Lovell hosts another podcast (see https://t.co/8rB9tIENvS), though it is not particularly mathsy.

[Julian Gilbey @JulianMaths]

@StellaDudzic 10.35 is probably understood as a date: it's 0.35 of a day into day 10 of Excel time (perhaps starting from 1 January 1900). 0.35 of a day is 8 hours 24 minutes! Entering 10:35 with a colon should do the trick!

[Julian Gilbey @JulianMaths]

@TolouShadbahr @TDLaajala @RannikkoAntti @MirttiTuomas @0ussamabatouche Congratulations!