If you’re doing a tutorial for CLI based stuff in a terminal - 2 CPU and 2 GB RAM should be plenty… But when you want to present some stuff around the GUI - then temporarily bump it up to 4 and 4 (4 CPU and 4 GB RAM)… I have a “jumphost” at one customer, running Ubuntu 18.04 (basically headless server install), 2 CPU, 2 GB RAM and only 16 GB HDD - that’s plenty…