Generally speaking, use the plural
students.
| Students should buy all the books on the reading list by the second week of classes. |
| In the second semester, students will be required to submit a ten-page report. |
However, when you want to emphasize the individual nature of the learning, such as in course guides that describe the final project, use the singular.
| Each student will be asked to prepare an outline of the second assignment, which must be presented to the rest of the class. |
In this case, if you need to use pronouns, use
they,
them and
their. This is more concise and inclusive than using constructions such as
he or she,
him or her or
his or her.
Therefore, not
| The student will present his or her assignment to the rest of the class. When he or she has finished, the rest of the class will have twenty minutes to ask him or her questions about anything that seemed unclear. |
but
| The student will present their assignment to the rest of the class. When they have finished, the rest of the class will have twenty minutes to ask them questions about anything that seemed unclear. |