Young geologists piece together the puzzle of plate tectonics in an earth science lesson. Given a physical map of the world, they search for land formations that indicate the location of different types of plate boundaries.

Every year, more than 14 billion pounds of garbage is dumped into the oceans of the world, most of which is plastic and toxic to ocean life. Lesson 32 in the series of 36 focuses on environmental concerns, specifically pollution. Under...