Mid-ocean ridges are fascinating places where lava pours onto the ocean floor, creating the longest mountain chain on the Earth. The discovery of mid-ocean ridges was also a scientific breakthough, explaining why continents move. This reading can be used for classwork or homework. It is designed for middle- or early high-school students who have already learned the basics about plates and plate movement. Grade 8 reading level. Three questions reinforce content and check comprehension.