@futurebird the more I think about, the more I think we may have used capital letters for vertices and lower case for angles as an unspoken convention. Like, maybe A, B, C for vertices and x, y, z for angles.

I've just checked my son's maths dictionary, and I can't see any vertices labeled in the angles or triangles sections.

It's entirely possible that it's any one (or several) of a hundred other things tripping up your student. Brains are weird and varied.

@jetlagjen @futurebird

A, B, C for vertices, α, β, γ for angles? But what would I know? It's all Greek to me!

Someone posted a link to this a while back; interesting in the context of the presentation discussion:

[#AltTextForMe - help!]

I thought it was obvious, but I'd seen in a Primary Maths Challenge (aimed at 9/10, 10/11 year old UK kids) … How many different isosceles triangles with whole number sides can you make from a loop of string 21 units long?
https://www.theguardian.com/science/2025/feb/17/can-you-solve-it-the-simple-geometry-question-that-fools-almost-everyone
:

@jetlagjen @futurebird

A, B, C for vertices, α, β, γ for angles? But what would I know? It's all Greek to me!

Someone posted a link to this a while back; interesting in the context of the presentation discussion:

[#AltTextForMe - help!]

I thought it was obvious, but I'd seen in a Primary Maths Challenge (aimed at 9/10, 10/11 year old UK kids) … How many different isosceles triangles with whole number sides can you make from a loop of string 21 units long?
https://www.theguardian.com/science/2025/feb/17/can-you-solve-it-the-simple-geometry-question-that-fools-almost-everyone
:

@hitsuyonai @jetlagjen @futurebird oh! Took me a bit. That’s just cruel

@jetlagjen @futurebird

A, B, C for vertices, α, β, γ for angles? But what would I know? It's all Greek to me!

Someone posted a link to this a while back; interesting in the context of the presentation discussion:

[#AltTextForMe - help!]

I thought it was obvious, but I'd seen in a Primary Maths Challenge (aimed at 9/10, 10/11 year old UK kids) … How many different isosceles triangles with whole number sides can you make from a loop of string 21 units long?
https://www.theguardian.com/science/2025/feb/17/can-you-solve-it-the-simple-geometry-question-that-fools-almost-everyone
:

@hitsuyonai @jetlagjen

@futurebird @3TomatoesShort @EverydayMoggie Copy/paste works too…but this is basically how every conversation I have with math teachers goes, and I feel bad because I don’t get it, and it must be annoying for them all. In high school my last teacher just said I don’t actually need to know it and put me in a basic class where we learned to calculate rent on a low salary. Now that was easy to understand!

@Bumblefish @3TomatoesShort @EverydayMoggie

The reasoning you did to make this conclusion:

That’s a moray (@Bumblefish@mastodon.scot)

@futurebird@sauropods.win @3TomatoesShort@disabled.social @EverydayMoggie@sfba.social The opposite one will always be the same size.

mastodon.scot (mastodon.scot)

... means you can understand geometry and congruent triangles.

To know those "slices" are equivalent is "Side Angle Side"

I think you just need to learn to like the compass better as a way to deal with lengths. It can be very powerful I'll show you an example. Someone posted a nasty trick question on this thread. Thinking about it with a compass makes the trick vanish.

@futurebird @hitsuyonai @jetlagjen Honestly kinda hard to think about how to text-describe this when it's primarily(??) a visual troll-- that it's drawing the triangle as having 2-dimensional volume, when in fact it pointedly does not.

Does just saying "triangle" do that enough, and make a strong enough "this is in 2D" impression? should I go back and add more spacial descriptors, e.g. saying the segment goes "down" from A to D?

@futurebird @3TomatoesShort @EverydayMoggie Infinite spiral of isosceles triangles, just eyeballed