Book Adventure is a fun, free way to motivate your child to read! Kids in grades K-8 can search for books, read them offline, come back to quiz on what they’ve read, and earn prizes for their reading success. Start your reading adventure
Khan Academy is a non-profit educational organization created in 2006 by educator Salman "Sal" Khan with the aim of providing a "free, world-class education for anyone, anywhere". Wikipedia