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David Butler
@DavidKButlerUoA
Lecturer at Maths Learning Centre, Uni Adelaide (my views here). Grad Dip Ed & PhD Finite Geom. Love maths and helping people learn. he/him #MTBoS #100factorial
Adelaide, Australia
blogs.adelaide.edu.au/maths-learning/
Joined September 2014
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    David Butler
    @DavidKButlerUoA
    Nov 15, 2024
    PSA I won't post new things here on Twitter / X any more. Not closing the account yet, but I'll only post new things over in the Azure Firmament.
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    David Butler
    @DavidKButlerUoA
    Jul 23, 2024
    I’m @davidkbutler.bsky.social if you want to follow me in another place.
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    David Butler
    @DavidKButlerUoA
    Jun 17, 2023
    A very large warehouse roof covered in snow, and a man with a shovel having cleared a tiny corner of the roof. The uncleared potion has a label that says MATH. The cleared portion has a label that says MATH I’VE LEARNED. The whole building stands in a giant field of snow with the label MATH THAT HAS YET TO BE INVENTED.
    A picture of a large roof top covered in snow, with one small corner shovelled. The shovelled corner is captioned "math I've learned". The rest of the snow is captioned "math".
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    MathMatize Memes
    @MathMatize
    Jun 13, 2023
    Even with a PhD
    425K
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    David Butler
    @DavidKButlerUoA
    Jan 29, 2022
    I’ve never seen this geometric proof of the difference of two squares factorisation before and I love it.
    At the top of the photo is a drawing of a square with sides labelled b with a smaller square sitting in its corner with sides labelled a. The space between the two squares is shaded and cut by a line from the corner of the small square to the big square. Those two shaded pieces are rearranged into a rectangle at the bottom of the photo. The long edge made of two parts, one labelled a and the other labelled b. The short edge is labelled b-a. So, the space between the two squares of areas a^2 and b^2 can be cut into two pieces and rearranged into a rectangle with sides b-a and b+a.
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    David Butler
    @DavidKButlerUoA
    Feb 7, 2020
    222 just does not FEEL like it’s 6×37.
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    David Butler
    @DavidKButlerUoA
    Nov 27, 2023
    I am (possibly unreasonably) proud of this problem I wrote for the course: Find the length of the path shown by the solid black line in this picture.
    A large circle is divided into eight equal segments by dotted lines. A smaller circle touching the first circle is divided into six equal segments by dotted lines. A solid black path travels along the diameter of the large circle, then 3 eighths of the way around the circumference of the large circle where it meets the edge of the small circle. Then it travels 4 sixths of the way around the circumference of the small circle, and along a radius of the small circle to its centre. The diameter of the large circle is labelled "6 cm" and the radius of the small circle is labelled "2 cm".
    124K
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    David Butler
    @DavidKButlerUoA
    Jun 22, 2022
    Replying to @jkiggins @ShardsL and @UOW
    Well THAT’s cool! Can we have a photo next week to compare?
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    David Butler
    @DavidKButlerUoA
    Feb 10, 2021
    All maths is advanced maths. From the perspective of your student, the maths they are learning now is the most advanced maths they have ever learned. Give them the credit they deserve.
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    David Butler
    @DavidKButlerUoA
    Sep 14, 2020
    I am not ok. I don’t have the energy to explain why, and I don’t have the energy to listen to advice. But I just want you to know I am not ok. Because I also don’t have the energy to pretend I am ok.
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    David Butler
    @DavidKButlerUoA
    Mar 17, 2019
    My 10-year-old daughter was rolled in a ball crying yesterday, because of her maths homework. Maths class should not make people feel this way.
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    David Butler
    @DavidKButlerUoA
    Sep 3, 2021
    Me: My feelings about a maths thing. Mathematicians of Twitter: Oh that’s easy when you realise it’s just a floximatic arklesquish.
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    David Butler
    @DavidKButlerUoA
    Dec 11, 2020
    Good teaching isn't spectacular. It's hundreds of little things each day, each moment. Most of it nobody can tell is there unless you point it out. Mostly you can't take a photo of it, or even describe it in a tweet. But it's there, it's real work, and it does make a difference.
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    David Butler
    @DavidKButlerUoA
    Apr 1, 2020
    Daughter C (11 years old) just finished the whole set of Jenga Views puzzles. She was very proud of herself. (Puzzles can be found here drive.google.com/open?id=1rPl5r…) #Homeschooling2020 😍
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    David Butler
    @DavidKButlerUoA
    Apr 2, 2023
    I am rather surprised that the red path is the same length as the blue path. cc @blatherwick_sam
    Four squares lined up next to each other to make a rectangle. The left edge and top edge of the rectangle are coloured blue. A red zigzag goes from the bottom left corner, to a point one third the way along the top edge of the rectangle, to a point two thirds the way along the bottom edge of the rectangle, to the top right corner.
    228K
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    David Butler
    @DavidKButlerUoA
    Feb 6, 2022
    It is a common belief that a person who is “good at maths” will understand everything without putting in any effort, and this belief hurts everyone.