Hello,
I started teaching myself sign language from 4th grade until 12th grade, and then took some private lessons in the community in the summer time at the local recreation place.
I taught myself by just buying the books, and going over and over it from the beginning. I also got from the library vhs tapes with little red riding hood, ect so that i could see the language in action. I practiced with my friends a lot too, and taught them.
My advice......if your s.o. is interested, and you dont want to commit to a class because of time, ect. go on ebay. look under sign language. there are tons of books, dictionaries, phrase books, videos to learn, even a video series to learn from. Plus there are kid video's too in sign. It makes it so easy to learn. And to be quite honest, it is a very easy language to understand. A lot of the signs look/act just like the object you are signing.
As far as kids go......I've got 2....a 2 1/2 yr. old, and one that is 15 months old. I started the kids early with sign language, just because i learned it, and the research shows that it is really benefecial. There isnt any "lag time" with language, in fact they learn to talk quicker, and understand a lot more than their counterparts. Plus, the comprehension of language, and just in general is far greater than not learning the language. The effects are seen well into grade school. It has to do with spacial skills, ect.
Personally, it's cute to see them use some signs together or with me.
I think you'll find as you learn and use it,....it becomes addictive.
Check out this website:signwithme.com
plus check out google.com for info and websites about baby signs or online sign language courses or dictionaries. The internet is chock full of stuff
Good luck!