I asked some other higher-ed instructors (not all foreign language teachers) about offering extra credit. Most sided with me and said that they just don’t do it. Those who do give extra credit will only do so if it is available to the entire class, not just one student who is insecure about his or her grade.
It is acceptable to offer extra credit for attending events that are somehow related to the course content. For example, it is reasonable to offer extra credit to Spanish students if they attend a showing of a film in Spanish. They have to provide their own transportation, pay for their tickets, and spend an hour or two of their own time engaged in an activity they might not do otherwise. But they have to do something to prove that they were actively watching the film, not sleeping, texting, or listening to music on their iPod. In my experience, only a small percentage of students take advantage of such offers for extra points, and they are usually the ones who would want to do those extra activities anyway.
So, actually, I have no problem with this type of extra credit. The kind of extra credit that is unfair is the kind that will give a student a higher grade than what they deserve. I’m referring to the student who does not put any effort into completing assignments, or who is not capable of comprehending, speaking, reading, or writing a foreign language well enough to meet the criteria for the grade that they desire.