Now you see it, now you don't. Our moon seems to pull a disappearing act from time to time—but why? Take your seventh grade scientists above and beyond to discover the truth about the moon and the role it plays in Earth's little...

Adolescence and teenage years are very difficult in terms of emotions, primarily due to the amount of change going on in growing teens' lives. Guide middle schoolers through disruptive changes and transitions with a set of activities...

By the end of this section, you will be able to interpret a phase diagram; state Dalton's law; identify and describe the triple point of a gas from its phase diagram; and describe the state of equilibrium between a liquid and a gas, a...