check / card / envelope

Draw a square in the air that is about the size of the item you are representing.

Note: if you mean "check" as in "A teacher check's his students papers," -- see "INVESTIGATE / RESEARCH / CHECK"

CHECK (or envelope or card depending on the size of your square)

Animation:

CHECK (version 2)
Place a downturned "C" hand on the palm-up left flat-hand. Slide the "C" hand forward a few inches.
Note: This sign happens to also be one of the versions of the sign "CAKE."

American Sign Language University ASL resources by Lifeprint.com Dr. William Vicars