Hello all,
I am a serious high school vocalist interested in going to conservatory and studying for a career in opera. I have been getting involved in the Washington National Opera lately and am wondering if being a supernumerary would be a good idea. Would it look good on my resume? Does anyone have any experience with this? If I decide to do/ get offered a part as a supernumerary I was thinking it would give me a really good learning experience for me.
By all means, do it if you want to, but it’s not going to have any impact on your “resume” when it comes to school. A “super” doesn’t sing, they are the ones who carry spears and buckets, gather around the fainting soprano, arrest the tenor, etc. You’ll have fun,get to see what goes on backstage, and enjoy the opera from a great vantage point to the extent that they allow you to remain in the wings when you’re not onstage. If you are considering going to school for vocal performance, grab any opportunity you can to see/hear opera. American students are far behind their European peers when it comes to that- many students here get to school never having seen a live opera, and a good many pick up their degree never seeing any more than the productions they take part in during their undergrad years.
If you can fit this into your schedule without letting your studies slide, by all means, go for it!
Ahh I still learn new things every day…I have never seen this word “supernumerary” in my life. 
I think any experience like that can have value. At one of the schools where my daughter auditioned, they explicitly said that her varied experience on her resume made her stand out. She did a 2-week stint as a stage management apprentice in a big musical theatre company, and that is one of many things on her resume. If you have the time, it certainly can’t hurt, and like @Mezzo’sMama said, there is much value in seeing/hearing operas up close and personal like that!
Just so you are aware @sopranogurl- and anyone else who may be considering working in a professional house: some jobs are required to join a union, and that can make it difficult for you later on as a student or a young artist. I know that the supers at the Met and the Chicago Lyric Opera are union members.