The Shapes Gallery in PowerPoint consists various shapes, both open and closed. Most of the shapes in this gallery are closed shapes, for example, a Rectangle, an Ellipse, and a Triangle. There are also a few open shapes such as the straight point to point line. Also, there are some drawing tools let you draw both open and closed shapes — these are the Freeform Line, Curve, and Scribble tools. In addition, you can convert any closed shape into an open shape and vice versa, as you will learn in this tutorial.
Learn how you can open and close paths for shapes in PowerPoint 2007 for Windows.

