A majority of U.S. college graduates don’t know the length of a congressional term, what the Emancipation Proclamation was, or which Revolutionary War general led the American troops at Yorktown.

The reason for such failures, according to a recent study: Few schools mandate courses in core subjects like U.S. government, history or economics. The sixth annual analysis of core curricula at 1,098 four-year colleges and universities by the American Council of Trustees and Alumni found that just 18% of schools require American history to graduate, 13% require a foreign language and 3% economics.