NASA has a website about astronomy called StarChild: A Learning Center for Young Astronomers. The site is offered at two different reading levels.
Geology.com has a page about rocks that has lots of photos and information about igneous, metamorphic and sedimentary rocks.
The Rock Cycle is an interactive website by Interactives about rocks that has lessons about the three main types of rock, how to tell the different rock types apart, and how rocks change from one type into another.
NeoK12 has videos and quizzes about identifying rocks, the rock cycle, and the different types of rocks.
Educationpossible.com has 10 Volcano Activities for Middle School to help students learn about volcanoes.
Primaryhomeworkhelp.co.uk has resources for learning about volcanoes, including an image that shows the parts of a volcano, and a list of vocabulary words.
BBC Bitesize has lessons about the atmosphere, including a reading section, a glossary, an activity, and a test.
Homeeducationresources.com has a free 14-page free printable packet about the earth’s atmosphere.
Primarythemepark.com has a great collection of weather videos for kids.
Thecraftingchicks.com has instructions and a free printable to make a Weather Chart Kid Craft to keep track of the weather.
Scholastic.com has a free printable chart for keeping track of the weather.
Web Weather for Kids has activities and games for learning about different cloud formations.
Cloud Quiz - Quizlet has online flashcards for the different types of clouds.
SnowCrystals.com has lots of information about snowflakes, and beautiful photos of snowflakes. There is also a page with instructions on how to make paper snowflakes that look like real six-sided snowflakes.