Which framework would you use to teach Comp-sci sophomores about REST API designing?

Hello Hashnode, this is my first post here :)! I'm doing soon a workshop for my friends who are grad student but have no experience in real world programming.

I have a few years of experience with Express, Rails and more recently, Phoenix (Elixir) but I feel confident enough to teach them in any other framework if it suits the purpose of them learning.

They are already used to working with basic algorithms and know a few about relational database modeling.

My main purpose of this workshop is to bootstrap them into the web development world giving some basic understanding of HTTP, API design best practices, devops, etc...

I'm really leaning toward Rails since it does all the (not yet) necessary to understand work for us. So, any suggestions?