"With ScratchJr, young children (ages 5-7) can program their own interactive stories and games. In the process, they learn to solve problems, design projects, and express themselves creatively on the computer." (Free)
Rodocodo
"A free coding game for kids (aged 4-11) that makes learning to code fun and easy. Neither you or your class need to know anything about coding to get started." (Free)
Code.org
"Explore the world of computer science with engaging videos, self-paced tutorials, programming activities, and more for all ages and experience levels!" (Free)