neoK12 has educational videos, lessons and games for k-12 students in topics including physical science, life science, earth and space and human body.
BBC KS2 Bitesize is aimed towards students from 2-6 and has games, videos and articles in topics including living things, materials and physical processes.
Kids.gov has articles, games and videos on topics including environment, life science and earth science for students in grades 2-5.
EIA Energy Kids is a great resource for students to learn about energy and has articles and other fun information for students in grades 2-6.
Cycles of the Earth System is designed for students in grades 2-6 to learn about all the different cycles on earth including energy balance, carbon cycle, rock cycle, ocean circulation, atmosphere circulation, water cycle and the nitrogen cycle.
Aspire Cosmic-Ray is a place for students to learn more about the moon cycles, as learned in grade 3.
Solar Eclipse and Lunar Eclipse has great information to use for study at home.