This model of a hat will be known to many people. I learned it as a child. Learning to fold a hat like this should be known to everybody. It is very easy. Use e.g. an old newspaper, but not one your parents still want to read.
First, we take a rectangular piece of paper
Here I take an A4-size paper. Other sizes with slightly different ratios
between length and width will also be OK. It is very fine to use a newspaper!
Then, fold it
in two, over the long side.
making a little crease halfway the fold I made in the previous step, such
that I know in the next step where to fold.
Now, fold the corner to the middle. The crease in the previous step shows where.
Note: the open side is below at the bottom side, i.e., the side I do not fold.
And fold the
other corner also to the middle.
Fold the flap below the corners up.
The crease is made at the place of the underside of the two corners we just
backside up, and fold the flap at the backside also, similarly as the front
And my hat is ready!
This one is a little too small for me.
If you want to go on: this hat can be turned into a boat by a little more folding.