Slack in the Classroom

I’m planning on trying out something new this year. Instead of focusing on Remind or even email, I’m going to see how well Slack works in the classroom.

What’s Slack

Let’s start with the basics. What is Slack?

It’s an online group chat tool. Across the left are the different rooms that you can join. The middle is where all the talking happens.

Slack screenshot

Why not Remind?

I’ve used Remind for the past couple of years, and it does a decent enough job for what it’s designed for. When I want to send out messages to students, or remind them of something, it’s not a bad tool.

What I found though is that Remind is pretty much a one way street. Sure, students could send me messages through Remind, but very few did. And there wasn’t any interaction between students.

Not that this is a fault of Remind. It’s just not what the tool was designed to do.

Why Slack?

One of the things that I don’t feel I do as good of a job as I could is hooking what we do in the classroom back to the real world. And computer science should be something that ties into the real world very easily. But we sometimes get so focused on labs and small projects that the bigger picture gets left behind.

Slack is a tool that’s used out in the real world. This gives it, in my mind at least, a huge step up over tools like Remind that are built specifically for educational use. It’s likely that students will be using Slack once they leave my room and are programming professionally.

Message Length

Remind has a max message length of 140 characters, which makes sense because it’s built like a text messaging app. But that’s just not enough for the way I want to interact with students.

I looked and haven’t been able to find a limit on Slack messages. The only limit I can find is a 16k limit on messages posted through their API. So that could be up to about 16,000 characters. Although that may just apply to the API. Either way, it’s a lot.


Not sure how important this is for most people, but I really like writing in markdown compared to basic rich text editors. Heck, I’m writing this post in markdown using Typora.

When I’m typing being able to bold something by typing ** bold text ** and it will be bold text is faster than having to move the mouse and click on the B or even ctrl-B.

Source Code

This may be the biggest one. I was looking for a good way to release solutions for labs. In the past I’ve written solutions as GitHub Gists and then embedded them into a Canvas discussion using an iframe. It works well enough, but was more time consuming than I’d like.

Going back and using markdown makes this a little easier with code fences.


public static void main(String[] args) {





public static void main(String[] args) {

when it’s rendered in markdown.

Even better though is when you paste in a Gist URL. The first time you paste a URL to a Gist it will ask you to connect your GitHub account. After that the Gists will embed like this.


Gist embedded in Slack

Since I’ve already saved most of my solutions as private Gists, this seems like a perfect way to handle posting solutions.

Student Interaction

The biggest downside to using something like email or remind, or even the discussion boards in Canvas, is that almost all interactions went either to or from me.

I’m hoping that using Slack will open up the students and get them talking rather than just asking me for help. Of course, that remains to be seen since I’m writing this about 2 weeks before I meet my students for next year.

Downsides to Slack

To paraphrase Randy Pausch, I can’t be all sunshine and roses or I’ll lose my credibility. So yes, there are a few negatives that I can see. I’m sure this list will grow as I use Slack next year.

Separate App

It’s another tool for students and parents to download and create accounts.

This is probably the biggest miss I’m going to have switching from Remind. Yes, Remind is a separate app and login as well. But most students and parents already have Remind accounts. I assume most will not already have Slack accounts.

Free Account Limits

There’s no way that I can upgrade to one of the paid Slack accounts. Even with the educational discount it would still be $1 per student, per month. Even a conservative estimate of $1,000 a year would be way more than I could justify spending on essentially a chat app.

They do have a fairly generous free tier, and that’s where we’ll be living for the year.

The biggest catch with the free tier is that there’s a limit of 10,000 messages. Once someone posts # 10,001 the old messages start rolling out of view.

I’m not sure how much this is going to matter though. If the students really buy into Slack we might hit 10,000 messages pretty quickly. If they don’t that might be enough messages for a few years.

It does look like there are ways to download archives, and I may look in to that as a possible solution to keeping old messages around.

Work in Progress

So that’s where I am for now.

I’ve got the Slack account setup and have made rooms for each course, plus a couple of extras. I’m optimistic that Slack is going to work out very well in class this year. Guess time will tell. I probably should go ahead and put a follow up blog post on my to do list for a few months from now to update with how it’s going. Newsletter

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