Aristo

Aristo is a system that answers questions from standardized science exams at multiple grade levels. The process involves three basic functions: (1) an ability to acquire and process facts into a structured knowledge base; (2) an ability to 'understand' exam questions and analyze their accompanying diagrams; and (3) an ability to answer questions using entailment, statistical analysis, and inference methods.

Source: http://allenai.org/aristo/