Credits and licence
OpenStax
The College Algebra lessons on Quarry School are adapted from College Algebra 2e by OpenStax, Rice University, used under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International licence. Access the book for free at https://openstax.org/books/college-algebra-2e/pages/1-introduction. The lessons rewrite and reorganize that material in plain words with new pictures, worked examples and checks; they are not endorsed by OpenStax or Rice University.
The licence these lessons carry
Because they adapt share-alike material, Quarry School's course lessons are published under the same licence, CC BY-NC-SA 4.0: you may copy and adapt them for non-commercial use with attribution to Quarry School and to OpenStax, under the same licence. Every worked problem on the public pages is original to Quarry School.
Fonts and code
The typefaces are licensed under the SIL Open Font License (see fonts/LICENSE.txt). The site's own code and explorers are Quarry School's.