The contra-alto clarinet is a member of the clarinet family. It may also be spelled contralto. It has a pitch one octave lower than the alto clarinet. It is an E flat instrument.
Due to the fact that often times in high school band music there is no contra-alto music written, there are a few techniques that have been discovered to allow someone to still play the contra-alto. One is to play off of the E flat baritone saxophone music. Another is to transpose tuba music. The tuba is a C instrument. Because of the differences in treble clef and bass clef, you can simple read the bass clef as treble clef music. This takes care of most of the transition from tuba to contra-alto. You must also add three sharps to the key signature. For example if the original key signature had two flats, the transposed key signature will have one sharp. If you are totally lost /msg or ask your band director or a musically inclined friend.
All in all, I think the contra-alto is a very cool instrument. It has a very low, deep sound, that sounds awesome in some songs. It allows you to play the great basslines usually reserved for brass instruments on an easy to play woodwind.
I will admit that sometimes the bassline is not nearly as interesting as I have made it out to be. When this occurs, you can do one of two things: play what is written, or make up your own part, while betting with the person sitting next to you how long it will take the director to notice. Note- I have only tried this in high school band, do not attempt in a professional setting.