What Does It Mean When a Class Has Variable Units? (3-5, etc.)
Sometimes you will see classes listed for variable amounts of units, such as 3-5. It's not a typo, but it may mean different things!
What do variable units mean?
When a course is listed with variable units (such as 3-5), it usually means one of two things:
Case 1: Workload Variation
The number of units depends on the amount of work you will do in the course. For instance, students enrolled in the 3 unit version of the course may have to write just one paper, but students enrolled for 5 units may have to write a paper and also give an in-class presentation. If this is a true variable-workload class, the differences in workload should be explained in the course syllabus. Some classes with a range like 3-5 units may be taken for 3, 4, or 5 units. Some may only be taken for 3 or 5 units. If the difference between units is unclear, but sure to speak with the course instructor. You must decide which unit version of the class you wish to take by the Week 3 Add/Drop deadline.
Case 2: Different Student Groups
Some courses are designed to allow you to take the course for a different amount of units depending on what student group you're in: for example, whether you are an undergraduate or a graduate student, a major or a non-major, etc.
For example, CS 106A may be taken by graduate students for 3 units, while undergraduates must enroll in the course for 5 units. The amount of work is the same, but you must select the option appropriate to undergraduates in order to receive a grade. Note that this kind of variable unit course is most often found in the Computer Science department. It is far less common in other academic departments.
To give another example, English 12A must be taken by English majors for 5 units. If you're not an English major, you can choose whether to take the course for 3 units or 5 units. There will likely be a difference in workload for the 3 and 5 unit versions, as mentioned above.
Often when there are different enrollment options for particular student groups, they will be explained in the course description on ExploreCourses, usually by searching for the course and then clicking on the blue "Schedule for [course]" link. Check the "Notes" section for details. For example, under "Notes" for CS 106A is the detail: "May be taken for 3 units by graduate students." Reading the Notes for any given class, especially courses with variable unit counts, can save you a lot of heartache and headache.
Not Sure? Ask!
Whatever the situation, it’s always good to check with the instructor when it’s a variable unit course and ask what the difference means. You can only adjust the number of units you are taking through Friday of Week 3 (the Final Study List Deadline), so make your decision and make sure your record in Axess is correct by then.
When you are enrolling several weeks in advance, it's fine to pick a temporary number of units, just be sure to adjust it later as you get more information.
How many units should I choose?
If the course has given you a true "workload variation" choice, then it's up to you. Think about your total course workload this quarter and how much time you think you'll have to devote to the assignments.
If you are taking the course to fulfill a Ways requirement, you must usually take it for at least 3 units, but there's no need to take on more than that unless you want to. (The exception is Way-CE, which only requires 2 units total.)
If the course is in a field you might like to major in someday, be sure to look up that major's requirements on either the Stanford Bulletin or on the department's website. In certain cases, you will need to take the course for the maximum amount of units if you'd like it to count towards your major.
When do I have to decide?
You must make your final decision about which unit version of the course you'd like to take by the Add/Drop deadline, which is always 5 pm on the Friday of week 3. It is generally not possible to decide to change unit count for a course after that deadline.