While active labwork in an out-of-school lab with direct (“hands-on”) experience may have positive effects on achievement and motivation, it is unclear whether the optimal time of day may intensify these effects. Adolescents' individual diurnal preferences indicate later times of day as optimal but lessons are in the morning. In the present study, the effectiveness of labwork was examined regarding diurnal preference, achievement, and emotional variables (N=473 students; age: M=15.3, SD=0.7) in 18 secondary classes in a morning and an afternoon course. Data were gathered on achievement (starch chemistry, pre and post) and on state motivation. Results indicate a synchrony effect (interaction of time of day and chronotype) in achievement and state motivation. Evening types have worse achievement, lower interest, and lower joy in the morning, but there were no significant associations between chronotype and the outcomes in the afternoon. Since adolescent evening types can learn better and are more motivated in the afternoon, schools should offer more learning opportunities in the afternoon.