I use the free non-profit web portal Khan Academy for my Adult High School night classes. It helps those students who need more refresher classes, and also those students who are ready to skip ahead of where I am in the lectures, so that I can focus on creating one lesson plan and then work individually with other students who need in-person attention. I also use KA activities as on-line worksheets, and for students who cannot make it to class due to work, surgery, car-accidents, family emergencies, etc.
Because my students can use the app with or without registering, it makes their lives easier, and facilitates my sending them assignments for things like Learn Storm, which helps them above and beyond their content and test-taking studies.
I am still in a precarious situation myself, and so am currently unable to donate, but I will dare to ask you, my dear readers, if you are able, to please give just a bit of your abundance, to help me and my students build a better society, a kinder society, and a better, kinder, safer world for all of us.
My Very Warmest Wishes,