Sphere

(a)   is a sphere that contains all the rocks and minerals on the earth.

(a)   is a sphere that contains different layers of gasses.

(a)   is a sphere that contains all living things on Earth; including humans.

(a)   is a sphere that contains all the water on the Earth.

The Greek word Hydro means...

What is the layer of gas surrounding the Earth called?

A Polar Bear is standing on a glacier. What two spheres are interacting?

A bird flies through the sky. What two spheres are interacting?

Cars, buses, and airplanes release harmful chemicals. What kind of pollution do these vehicles cause?

What are the four major domains or systems of the Earth?