Start with a rectangular sheet of paper
Fold it in half lengthwise
Crease the fold firmly
Fold the top left corner down to the center crease
Fold the top right corner down to the center crease
Fold the bottom front flap up over the triangle
Flip the paper over
Fold the bottom back flap up over the triangle
Tuck one flap into the other if needed to secure it
Open the bottom and shape it into a hat