The earliest scientists first observed the waves that earthquakes produce before they could accurately describe the nature of earthquakes or their fundamental causes, as discussed in Lessons 1–5.

We visit a recording studio to explore the properties of sound. Unit 6 Segment B: Sound Waves Properties We visit a recording studio to explore the properties of sound. We explore the speed of sound ...

Look at that mountain! Imagine you are standing at the base of a volcano looking up. You were told that the volcano isn’t going to erupt anytime soon, but you notice a little bit of smoke (or is that ...