Soft Deadlines: Slip Days and Extensions

This is the first in a planned series of posts about ways to reduce deadline-related stress without sacrificing student learning. It’s something we’ve been actively working on for several semesters now, and hopefully these posts will start a conversation about new ideas and tools toward this goal.

This post starts off the series with a bit of background motivation on why we’ve chosen to use soft deadlines in our classes, and a quick overview of the main strategies for implementing them (slip days and extensions). Future posts will go into more detail on those strategies and things we’ve been working on.

Proficiency-based learning is impractical

I’ve been seeing a lot of talk recently about proficiency-based learning (previously known as mastery learning). The high-level idea is, if a student hasn’t fully learned some material yet, we should let them keep working on it and only move on to future topics once they’re comfortable with the material. In theory, it’s a great idea, but it’s hard to implement in practice (much like the classic two-sigma problem). The unfortunate reality is people spend a limited amount of time in school, and there often isn’t enough time to let people work at their own pace until they’ve learned all the material. This is especially true in higher education, where every additional semester translates to thousands of dollars in tuition.

Proficiency-based learning is best if there aren’t deadlines to learn material, but in practice, there is always one deadline at the end of the semester (or at the very least, when a student graduates). A proficiency-based learning semester with no deadlines (except the one at the end) could easily lead to mass procrastination and a panicked class scrambling to learn an entire semester of material in the final few weeks.

Hard deadlines are bad

On the other extreme, we have hard deadlines: students have to finish an assignment (and thus learn the corresponding material) by a certain date, or else they get no credit for that learning. I could probably make an entire post detailing the problems with this approach, but for starters, they’re extremely stressful and inflexible for students. Stuff happens in real life, and students will miss deadlines for reasons out of their control. It doesn’t feel fair to penalize people for that.

Hard deadlines also make it easy to fall behind: if you’ve missed a deadline, you still have more unchanged deadlines coming up, but you might have to put in extra work to catch up on the topics you missed. That creates a cascading effect that is very stressful and particularly harmful to marginalized students.

Finally, the idea that you can’t get credit for learning if you learn some material after an arbitrary date is antithetical to proficiency-based learning, and it does feel pretty unintuitive.

Soft deadlines

So, how can we eliminate the stress and arbitrary learning restrictions imposed by hard deadlines, without running into the practical issues associated with proficiency-based learning (namely, making sure that all the learning still happens in one semester)?

The best answer I’m aware of is to implement soft deadlines. These deadlines act as forcing functions to avoid procrastination and generally keep students on track to complete all the material by the end of the semester, but the key is we don’t punish students heavily for missing these deadlines. We build some slack into our classes so that it’s possible to fall behind and still catch up without being penalized heavily, and we make sure that students don’t lose credit for extenuating circumstances outside of their control.

The rest of this post covers a few ways we’ve tried to implement soft deadlines, and the benefits and drawbacks of each approach.

Slip days

Slip days have been around at Berkeley for a long time now. The idea is, every student starts the semester with a set number of slip days, and they can use a slip day to extend a deadline by one day. This builds flexibility into the deadlines and gives students some freedom to choose where they want or need to use their slip days.

There are a lot of nuances to slip days that we’ll probably cover in a future post, but they’re a great way to make deadlines more flexible without students falling too far behind.


The other component to soft deadlines are extensions for students. Again, designing an extensions policy could easily take up an entire series of posts, but the idea is to let students request extra time on assignments when they need them and to be generous in granting those extensions.

Unlike slip days, extensions are a little harder to scale to a large class, and that’s something that CS 161 is going to be working on this semester.