A、Subject areas are separated. B、Classes are held in the open air. C、Mother Earth class covers math. D、Teachers prepare classes

International Baccalaureate schools began decades ago as a way to teach the globe-trotting children of the international diplomatic corps. Now, IB schools welcome all kinds of children. The program combines what are considered to be the best teaching techniques, a rigorous curriculum stressing writing and analysis, and an international perspective.
   The goal is to develop involved, articulate global citizens. Bloomfield Hills is a wealthy suburb of Detroit, Michigan. The school district here has set up an International Baccalaureate program at Lone Pine Elementary. At IB elementary schools, subjects like math and reading are not taught separately. Subject areas are integrated, so lessons in "Mother Earth" class, for example, cover vocabulary, literature, history, and ecology. The program also breaks down the proverbial classroom wall. Teachers are required to compare notes and plan classes together. That’s a "best practice" that IB schools adopted because it develops teachers’ skills.
3. What does this news item mainly deal with?
4. What can we know about the IB elementary schools?