What are the principals of Walter Gropius' architectual work?

Question:

What are the principals of Walter Gropius' architectual work?

Please help me on this one... I have a very important exam tomorrow and it would really save me some time...

Best Answer - Chosen by Asker: His buildings are characterized by an adventurous use of modern materials: - that is steel, concrete and glass. He was the principal innovator in the use of a glass screen to form the entire outer shell of a building, thus admitting the maximum light.
His work is always distinguished by a classic restraint and excellent proportions -
Important buildings he designed include : In 1926 when director of the Bauhaus Arts and Crafts school he designed the school's buildings (glass screen on the facade extended for three storeys); Dammerstock housing scheme in Karlsruhe. Left Germany 1931 settled in England; partnership with Maxwell Fry - designed - among other buildings - London Film Labs. at Denham; in USA designed Pennsylvania Pavilion at 1939 New York's World Fair. (Just some examples)