1. Jump on a site like CodeAcademy and try teaching yourself a new computer programming language.
2. Teach yourself a new language. A language you have always wanted to learn.
3. Teach yourself a hobby, like playing the Guitar or something.
BTW, for most people, unless you have traveled, Quarantine doesn't necessarily mean you HAVE to stay home and not go outside (I know this kind of goes against the definition, but I hope most will know what I mean). You can go outside provided you practice social distancing / stay away from others / do things on your own. I've been tempted to head out north (I'm in Canada) and do some sight-seeing or explore towns I haven't explored before. Must be a ghostly sight with almost everything being absolutely deserted.
If this is the case, I wonder why some are trying to get cities and towns deserted.
A single person could safely go out to farm, buy stuff in store occupied by one seller, practice the social distancing in moderate gatherings in open space, etc
I really wonder why some are trying to make it look like it's forbidden to go outside, especially to work and buy things in places with good social distancing and other preventative measures