The ability to speak two or more languages is an asset that you should take pride in, but it is also important to be sensitive to your instructor and classmates in your shared learning environment. Whenever possible, use the language that all participants in the class can understand easily. In US academic settings, this language is English.
If you feel the need to discuss or explain an idea in your native language with one of your classmates, be sure to alert your instructor first. If you begin speaking to a friend in a language your instructor does not understand, your instructor may think that you are not paying attention (which is considered rude). Try to think of the class time as a regular opportunity to practice your spoken English.
Related topics:
Class participation
Working in groups
Showing respect for peers