I would also email to ask. I graduated this past May and am now working at a school with the special education students. I took sign language over the summer as well. I asked for a recommendation from my CSD undergrad professor, my supervisor for my job, and one from my sign language professor (all of which tie into speech). I emailed schools and asked if this was okay and they say that is totally fine. I think it depends on the school, so I would email them!