On a simple level: -They film (or create the animation) from two different angles, similar to how our eyes see things from two lenses, rather than one. -Then, when they project the image, they display two versions of the same movie from slightly different angles. -The 3D glasses force the eyes to each view a different image, which give the real life effect of depth. if someone is blind in one eye, then they can’t see the 3d effect because they are only seeing one angle of the movie. A good way to demonstrate how each eye sees things differently would be to have her focus on something with a vertical line, like a bookcase. Then have her close one eye and put her finger on the line of the bookcase. Once she has her finger on that line, have her close the open eye and open the close done. She will see that the finger “jumps”