It also models pumps in a pretty exaggerated way. Two pumps will prevent this basin from ever filling up despite constant rainfall, to the point of creating a concave water surface: https://imgur.com/a/PrYFJtP
I worked there until 10 years ago and it was quite rewarding. (In fact this interactive uses some of the "lab" framework code I worked on.)
The founder was inspired by Concord (Massachusetts)'s history of progressive educational experimentation, going back to the transcendentalists (Emerson, Thoreau).
They're based in Concord but they also have a Bay Area office, after merging with the nonprofit org that built CODAP (https://codap.concord.org/)
https://wildfire.concord.org/