1st, I want to say, I believe in what you say and sign should be a foreign language, but I can see where your school might not think that. I believe a good debator is someone that can perpair a debate for 1 side and still debate for the other side as well. They might be thinking along the lines for the writen language part, with both is the same, just speaking ASL grammer is not even close to English speak.
I can't remember the name of the book, but the sign language book that my wife bought me when we started dating stated that ASL was the 4th largest foreign language. I do know some states declear ASL is a foreign language, since the English language is based on speaking. If that book states that, then the goverment must look at ASL as a foreign language.
Also, out of dictionary.com, this is what I got from the following words:
American Sign Language
a visual-gesture language, having its own semantic and syntactic structure, used by deaf people in the U.S. and English-speaking parts of Canada. Abbreviation: ASL
Also called Ameslan.
[Origin: 1960–65]
English Language
n : an Indo-European language belonging to the West Germanic branch; the official language of Britain and the United States and most of the Commonwealth countries [syn: English, English language]
lan‧guage [lang-gwij] Pronunciation
–noun
1. a body of words and the systems for their use common to a people who are of the same community or nation, the same geographical area, or the same cultural tradition: the two languages of Belgium; a Bantu language; the French language; the Yiddish language.
2. communication by voice in the distinctively human manner, using arbitrary sounds in conventional ways with conventional meanings; speech.
3. the system of linguistic signs or symbols considered in the abstract (opposed to speech).
4. any set or system of such symbols as used in a more or less uniform fashion by a number of people, who are thus enabled to communicate intelligibly with one another.
5. any system of formalized symbols, signs, sounds, gestures, or the like used or conceived as a means of communicating thought, emotion, etc.: the language of mathematics; sign language.
6. the means of communication used by animals: the language of birds.
7. communication of meaning in any way; medium that is expressive, significant, etc.: the language of flowers; the language of art.
8. linguistics; the study of language.
9. the speech or phraseology peculiar to a class, profession, etc.; lexis; jargon.
10. a particular manner of verbal expression: flowery language.
11. choice of words or style of writing; diction: the language of poetry.
12. Computers. a set of characters and symbols and syntactic rules for their combination and use, by means of which a computer can be given directions: The language of many commercial application programs is COBOL.
13. a nation or people considered in terms of their speech.
14. Archaic. faculty or power of speech.
[Origin: 1250–1300; ME < AF, var. sp. of langage, deriv. of langue tongue. See lingua, -age]
I also looked up Sign Language and Spoken Language, and I got definitions out of both, but you want, you can get it from the website. The English language, based on the definition, is from the Germanic language, but ASL is souly based on the American culture, it not based on Germanic, just use the same spelling. I hope that helps a little.