The sign you are describing is used for that or it. You would look at your palm at the same time.
The same thing with the palm facing to the right or left depending on your nondominate hand is show. This is a directional verb and can be moved toward the person you are showing it to ie SHOW-ME, SHOW-HER
What is the nondominate palm flat with the index finger of the dominate hand sweeping across the palm from the thumb down.
What you are describing can also be used for owe.
Ask the teacher what she is using it for.
a good site to see the signs is
http://commtechlab.msu.edu/sites/aslweb/browser.htm .
You do not need to pay to use this site.
Also a good resource is the handshpe dictionary which can be bought at a bookstore. It shows the signs by handshape so you can flip through that section and find the picture and see the English concept.