Waterbomb Base

These are the first folds for the waterbomb. The dashed lines are valley folds, the solid line is a mountain fold.

The waterbomb base is the starting point for many origami models.  The frog, flowers, and a few airplaces all start with this shape.  Many model directions will simply say "fold a waterbomb base".  It is a simple base that involves two valley folds and a single mountain fold, and yields a triangle.

A valley fold is the only fold you can do with the paper flat on the ground, making the shape of a valley with the paper.

 Valley fold the bottom right hand corner up to meet the top left hand corner.  A valley fold is the only fold you can make with the paper laying flat on the ground.  It forms a shape like a valley.  Make a good crease, and unfold.

Unfold and valley fold the other diagonal line.

 Valley fold the bottom left hand corner up to meet the top right hand corner.  Make a good crease, and unfold.