The SAMR (Substitution Augmentation Modification Redefinition) model is a framework used to evaluate the technology being employed (or that you'd like to employ) in your classroom. Basically, it offers a way for you to look at how technology integration might affect teaching and learning.
A couple of years ago, I first encountered Slack in the context of a multiplayer augmented reality game community ( Ingress). At the time, I didn't quite get the need for Slack. It seemed like yet another chat platform, albeit one with multiple channels and group features.