Slack is a really useful communications tool for groups. The next time I run a MOOC I will use Slack (or an open source equivalent if I find one that works as well). This article looks at how Slack the company uses Slack the tool. Some lessons: signify consensus with an emoji. Slack uses the shrimp to do this (with the result that 'shrimp' has become a verb at Slack). Other emoji can be used for other tags. Slack also uses automation tools as much as possible. For example, "if you want to test something with these external participants, you can submit a request using Workflow Builder."