What do the most populated cities in the world have in common?
(Why are these the most common)

What part did glaciers play in forming the great lakes?

People make choices about how to use resources.

Which of the layers of the earth has the following three characteristics? i. it is a solid outer layer. ii. it is between 3 and 30 miles thick. iii. it is separated into plates. a. the outer core b. the inner core c. the mantle d. the crust