Fold a paper boat · Pulse Beat

A paper boat is a lesson in folding a rectangle into triangles. Start with an A4 sheet.

Fold it in half the short way, then unfold to make a crease. Fold the top two corners down to the crease to make a triangle on top of a strip.
Fold the strip at the bottom up on one side, and the other side behind. You now have a hat shape.
Open the hat and press the two bottom corners together to make a diamond.
Fold the lower corners up to the top, one in front and one behind, making a smaller triangle.
Open it again and flatten into a diamond. Gently pull the two top corners apart. The boat opens out.

Every fold is a reflection along a line, which is why the two sides match. The hull is a trapezium and the sail is a triangle: a boat made of shapes you can name.