At ages 11–15, 25 intellectually highly able youths studied high-school biology and 13 studied chemistry intensively for three summer weeks, after which their median score on the College Board's achievement test was 727 (biology) and 743 (chemistry). Four learned both subjects well in six weeks. Thus, the 34 participants were prepared to study the college level of the subject(s) that fall or the next. Results for 184 students taking biology, chemistry, or physics two summers later were comparable. For youths this able, the usual high-school science course is much too slowly paced. Completing the basic course well during the summer makes it feasible to start advanced work in the subject that fall and thereby score high on the College Board's Advanced Placement Program college-level examination the next May.