Here's a bunch of stuff specifically identified for kids but the general site is full of resources, books, movies, etc. that might be used as well. 200 Free Kids Educational Resources: Lessons, Apps, Books, Websites... | Open Culture
The following sites are excellent supplements our kids education, register as a teacher on the sites to monitor progress Khan Academy - Math lessons and assessment GooruLearning - FREE, All subjects, lessons (decent English material) [register yourself as a teacher] CK12.org - FREE, All subject lessons and assessments [register yourself as a teacher]