I taught American Sign Language at New Mexico State University for three years, before I move to Colorado.
Here I have a pdf that explains how to work with a deaf employee at your office, private companies, etc...
Every Sign Language is not the same in some countries.. Like British Sign Language and American are different but in Canada and USA have the same sign language in ASL.
When I taught American Sign Language (ASL), I always tell my students that taking another foreign language benefits you with your major in Psychology, Sociology, or Geography...a deaf person will always be happy if you know or little bit of finger-spelling or sign language.
If you happen to know a deaf person, please network him or her to me...I'd love to chat with that person.
There is no universal sign language in GIS, Geography, or in any major. Basically you and the sign language interpreter need to team up to make it up sign language like for example : there is no sign polygon so you would have innovate one. Polygon means shape with like area.
Sign for Geography here : Sign for GEOGRAPHY | ASL Sign Language Video Dictionary
Sign for Map : it varies by the deaf person in some areas in the United States but most common I have seen here American Sign Language (ASL) Video Dictionary - map
For GIS , you would have finger spell it G I S
I will add more sign for some of the words in Geography or GIS later on..
So long !