If a student needs help, they should ask the teacher.
Okay, I’m trying to contain my temper here. Pronoun basics, folks: they is a plural pronoun. It can refer to a group of males, a group of females, or a mixed-gender group. But it’s plural. Plural = more than one.
In the more grammatical past, that sentence would have read (without question):
If a student needs help, he should ask the
They (as well as their) has crept into common use as an attempt to level the chauvinistic playing field of English grammar. Most languages have the same problem. I’m on board with the spirit, just not the execution. Feminism is no excuse for butchering the language. So:
If students need help, they should ask the teacher.Bingo! Students = plural; they = plural
Or, awkward as it may seem:
If a student needs help, he or
she should ask the teacher.
In some cases, such as a long article in which this construction comes up frequently, an author will switch between he and she:
If a student needs help, she should ask the teacher. The student’s peers may not be equipped to give her the assistance she requires. She can’t always rely on a friend, however well meaning he may be.Before this paragraph leads the reader to identify a gender too closely with an anonymous example student, the author will switch genders in the next example:
After consulting with his friends, a student may find he’s the class genius.
Whatever method you choose, don’t resort to the lazy use of a plural pronoun just because you’ve heard it or (horrors) read it before.