Making a plain old square exactly the size that you want can be such a chore. Too much can go wrong.
Squares can become so many different things (think ALL origami) that it’s worth knowing how to make a square just the size you want without getting stressed out.
Here’s how to do it, via the photo essay, followed by the video tutorial.
Here’s a regular piece of copy paper. The first steps look like I’m heading towards folding a square whose side is already predetermined by the short edge of the paper, but no. Be patient. This is going to be a surprise. Trust me.
Fold that short edge to meet the long edge, making sure that your fold ends (or starts) exactly at that corner. What you are doing here is bisecting that corner angle. If you cut away that rectangular flap on the edge, and unfold the triangle you’d have a square, but this isn’t what we are doing now. (Doing that was a different post, )
Unfold the fold then make a mark to indicate size of the square you want to make.
What I’m going to write next sounds horribly complicated but it’s easy to see and do.
Curl over that corner that has the fold going through it, lining up that corner point with the fold line it is leaning towards, and also lining up the upper edge of the paper with that mark you made. Press the fold.
Here’s a closer to look:
Now draw a line that traces around that folded down corner.
There’s your square!
Confused? Here’s a video to watch:
Now make cool stuff.
Addendum: here’s a post that shows what I showed, plus another great way of making a square. https://mikesmathpage.wordpress.com/2018/01/23/a-fun-folding-exercise-for-kids-from-paula-beardell-krieg/