A MOOC with five thousand learners and one template

An online Python course enrolls 5,000 people. Every one of them gets a real Linux container, copied from the course template snapshot at signup: interpreter, exercises, a terminal URL, an editor URL.

By week two, 80% have stopped opening it. That's normal for a MOOC. On a per-seat dev-environment platform it's also a monthly line item for four thousand idle seats. On Hoody the idle ones share their disk blocks with the template copy-on-write, the kernel caches the interpreter once, and idle containers burn no CPU. The rented servers are flat-rate; enrollment doesn't touch the bill.

The 20% who keep going have a machine that's theirs for the year. The 80% have one too. It costs nothing to leave it there.

A learner who never comes back costs exactly what an empty chair costs.