This is a list of places on the vast internet where you can learn about science and/or math. Be sure to try removing parts of the url (ex. site.com/a/b -> site.com), checking github repositiories, and clicking links to see more stuff. Many sites here are pretty interactive and a fair amount are sandboxy. all of these are free.
general stuff
literally this site explorable explanations falstad's site testtubegames phet, but it's the dev directory concord consortium Physics Educational Software for Your Browser (yes that's the official title) Dissemination of IT for the Promotion of Materials Science Teaching & Learning Packages (I finally kinda understand what this einstien summation thingy is yay)quantum physics
a dirac equation simulator quantum circuit simulator quantum flytrapchemistry
chemagic moleculesbiology
well, there's basically no biology simulator out there, so just have chemagicoptics
ray optics simulatorfluids
2d water (and air)