University Corporation for Atmospheric Research
Ucar: Catching Snowflakes
Are you in a place where snow falls in winter? If so, try catching snowflakes. Then take a close look. Can you find two snowflakes that look alike?
NASA
National Aeronautics and Space Administration: Scijinks: Atmosphere
Activity describing how the Earth's atmosphere was formed, why it stays close to the Earth, and why the sky is blue.