instructive
     adj 1: serving to instruct of enlighten or inform [syn: {informative}]
            [ant: {uninstructive}]
     2: tending to increase knowledge or dissipate ignorance; "an
        enlightening glimpse of government in action" [syn: {enlightening},
         {informative}] [ant: {unenlightening}]
Source: WordNet® 2.0