publicly available json-rpc node for bitcoin-cli connection
There is a free bitcoin-cli sandbox at bitcoindev.network:


  Here is a simple sandbox environment for trying out the bitcoin command line interface! Select Start Scenario to bootstrap your own private instance! 


You can check out the on-line sandbox here:

https://bitcoindev.network/bitcoin-cli-sandbox/

Simultaneously they provide a docker container for it, so your students can go up &amp; running with their own daemon in a blink of an eye.