How do you craft trapdoors in minecraft?

A hatch, or trapdoor, is created by filling the bottom and middle rows of the crafting table with wooden planks, like so (image from the Minecraft Wiki):

The minecraft wiki calls them trapdoors.

Like doors or ladders, water cannot flow through them, even when open, though it's unclear if Notch will eventually add in this functionality.

http://www.minecraftwiki.net/wiki/Trapdoor