Almost any rectangle of paper will make a boat, but some float far longer than others. A sheet of ordinary printer paper is the usual starting point: it folds cleanly, holds a crease and survives a few minutes on a pond.

Thin paper, such as a page from a notebook, makes a lighter boat that rides higher but soaks through sooner. Heavier paper is harder to fold at the thick corners. Waxed or glossy paper resists water best.

The classic boat starts from a rectangle about one and a half times as long as it is wide. A square sheet works too, but gives a shorter, deeper hull.

The classic boat takes four steps and about two minutes. Press every crease firmly with a fingernail; soft creases are the main reason a boat falls open on the water.[1]

Figure 1. The four steps.

1. Fold the sheet in half from top to bottom.

2. Fold the two top corners down to the centre line, making a triangle.

3. Fold the bottom strips up on both sides, like the brim of a hat.

4. Pull the sides apart, flatten into a square, then pull the top points out to open the hull.

Set the boat down gently, flat on the water, rather than dropping it. A small stone or a coin in the middle of the hull lowers the boat and keeps it upright in a breeze.

Write a name on the side before launching. A boat with a name is easier to cheer for, and easier to find in the reeds afterwards.

Paper softens and sinks within an hour. Fish it out when the race is over, and leave the pond as you found it.

The end.

A thumbnail or the back of a spoon both work.