I have found that notebooks like Jupyter (http://jupyter.org) and especially JupyterHub (http://jupyterhub.readthedocs.io/en/latest/) are made to teach languages with a REPL from the browser.

> "With JupyterHub you can create a multi-user Hub which spawns, manages, and proxies multiple instances of the single-user Jupyter notebook server. Due to its flexibility and customization options, JupyterHub can be used to serve notebooks to a class of students, a corporate data science group, or a scientific research group."

I have grown less and less fond of Python but I still use Jupyter with other languages and I have it running on my personal server.