Some online learning sources for kids are E-LearningForKids.org, CK12.org, KhanAcademy.org and Arcademics.com. All are free, though students must register for an account in some cases.
E-Learning for Kids offers interactive lessons in math, computer skills, science, language arts and life skills. A lesson about blood lets kids click on each blood cell type to learn about it. Second graders learn about fractions a step at a time by selecting fruit slices and their numeric fractional equivalents. Life Skills lesson topics include bullying, depression and family.
CK-12 has free textbooks, practice exercises, simulations and online help. SAT test prep and higher-level subjects such as engineering are available.
Khan Academy's video-based instruction first teaches a lesson, then has interactive exercises. The system tracks progress so that students can continue from where they left off. Students have the option to skip around and select only specific topics.
Arcademics helps build skills through game-like practice drills. For example, students learning U.S. state capitals make a penguin jump to an iceberg in the shape of the state matching a given capital. A multiplayer dirtbike game gives practice in comparing fractions.