You take a rectangular sheet of paper (Din A4 or A5) in a color that you like. You lay the sheet horizontally in front of you, flip the right side to the left side, fold the sheet exactly in the middle and carefully position edge to edge. A rectangle, only half the size of the sheet of paper, now lies vertically in front of you.
You turn the folded paper so that it lies horizontally in front of you. Then you fold it again from right to left and fold it in the middle. Then unfold it again. In front of you is a rectangle with a clearly visible center line.
Take the right corner and flip it to the middle. Do the same with the left corner. The inside edges of the two triangles are touching. The paper that is in front of you looks like a house with a pointed roof.
Take the part that is under the triangles and fold it upwards to the stop or to the bottom edge of the triangles. You turn the paper over and do the same on the reverse side.
You turn the paper over and fold the laterally protruding corners. In front of you is a triangle.
Take the triangle, grab the center and unfold it into a little hat. Then pull it apart enough to overstretch it and make a square. The square lies in front of you with the point facing down.
Fold the bottom triangular piece up, but don't fold it exactly in the middle; instead, leave a margin about the width of a finger at the top so that the top and bottom triangles don't completely overlap. You turn the piece over and do the same on the other side. In front of you is a triangle whose two bottom corners are slightly rounded.
You reach into the hat again and pull it apart. You pull it out again until a square is formed.
Take the two outer tips of the square and pull them wide apart with both hands at the same time. Your paper boat is ready.