An educational program was developed with the hope of decreasing drug$-$use amongst teens. The program provided a survey to $13-$year$-$old subjects before the educational program and after the educational program $($if a subject missed the pre$-$ or post$-$ program survey, they were excluded from the data analysis$).$ The survey tested the subjects' knowledge regarding the dangers of drug$-$use. The program took $12$ weeks to complete and was offered during school hours. The goal was to determine if the educational program improved the teenagers' knowledge regarding the dangers of drug$-$use. What statistical procedure should be used?