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Lottery / Wait List Info

What to do if you are lotteried out of a CS class

If you are lotteried out of a CS class and would like to be put on the waiting list, find your course listed below and follow the steps for that course (the steps are different for introductory vs upper-level courses). 

In an effort to balance CS labs and lecture sections, occasionally students are moved from one section to another after pre-registration. Please check your schedule after lotteries are over to verify your registration. If we moved you into another section, your schedule was checked to ensure no course overlap. If you do not want to remain in the class, please drop it to make room for wait list students. If you want to try to get back into your original lecture section, or another lecture section, please follow the waitlist rules below.  If you just want to switch lab sections, see the info about Switching Lab Sections below.


Waitlist info for Introductory Courses: CS21, CS31, and CS35


If you are lotteried out of CS21, CS31 or CS35, you can be added to the waiting list. We almost always are able to make all waitlist add decisions by the end of the first week of classes. Often times slots open up during the first week, particularly in the fall semester, and we add in students from the wait list that follow our waiting list rules:

  1. Prior to the start of the semester, send email to Lauri Courtenay (lauri at requesting to be added to the waiting list for the course. Include:
    1. Which course you are requesting to be added to (21, 31, or 35).
    2. Specify all class sections and lab sections you are able to attend. Indicate both the time and the number, for example:
      CS35.1 11:20-12:55  TR   
      CS35.2 11:30-12:20  MWF    * 
      CS35.A 1:15-2:30    M      
      CS35.B 3:00-4:30    M     
      CS35.D 3:00-4:30    T      * 
      The more section options you have, the more likely you will get an open spot. If you list more than one section, you can indicate your preferred class and lab section with a star (*).
    3. List your name and graduation class year.
    4. Give a 1 sentence reason why you want to take the course.
    5. Did you pre-register and were lotteried out this semester? If so, also include the class section and lab section you were lotteried out of.


  2. To stay on the waiting list you MUST attend all meetings of one section of the class and one section of the lab during the first week.
    • Sign in on the waiting list attendance sheet in the class and lab.
    • If you can add more than one section, you only need to attend one section of the class to stay on the waiting list for all sections of the class.

We start adding students during the first week as slots open in the course. Often times we can add students after Wednesday of classes. We try to make all add decisions by the end of the first week of classes.

We drop registered students from these courses who do not attend during the first week of class. We do this to ensure we can add as many waiting list students as possible. This means that sometimes slots open up at the end of the first week of classes.

We give preference to first and second year students in CS21, CS31, CS35, and to juniors who applied for the CS major and minor and who were deferred because they have not yet taken CS31 or CS35.

We keep a history of waiting lists and we try to avoid lotterying out students who were lotteried out and who followed our waiting list rules in previous semesters. Unfortunately, we are currently not staffed to guarantee slots in future semesters for students who are lotteried out of CS courses. We try as best we can to accommodate as many students as possible. Your best chance of getting into a CS21, 31, and 35 is to preregister during your first and second year, and to follow the waiting list rules if you are lotteried out.

Waitlist info for Upper-Level Courses (Numbered above CS35)

Please follow these special instructions for Fall 2020.


Switching Lab Sections

For CS21, CS31, and CS35, if there is a waitlist:

We do not track the switching of lab sections. If you are interested in switching your lab section, please do the following:

  1. Find a student in the section you are looking to switch into (tip: use Piazza if your class is using it)
  2. Once you find a student who is willing to switch, send Lauri (lauri at an email with the following information (Cc the swapping student):
    1. Names
    2. labs currently registered for
    3. labs looking to move into for both students (swaps cannot be made without this information)
  3. Once the switch has been approved, both students will receive an email from Lauri
  4. When you receive the email, please complete an online add/drop form to get registered for the course

If there is no waitlist and/or for upper-level courses: Please contact the professor about switching.