Grades 1–8 commence each school morning with the “Main Lesson,” a two-hour period of intensive and focused thematic learning in which the core curriculum is presented when the students are most receptive and alert. The main lesson subjects (such as Greek history, Botany or American Geography) are taught in three- to four-week blocks. The teaching units are integrated and cross-curricular, and include activities to awaken and focus attention. This approach allows for freshness and enthusiasm, a concentrated in-depth experience, and gives the children time to integrate learning. Being taught in the morning Main Lesson enhances the knowledge acquisition of academic subjects, such as language arts, math, science and history. Daily math practice periods also occur in the morning when the students are most alert. The afternoons are often used for arts and crafts, outdoor activities, sport and practical work. Skill-building subjects that benefit from regular practice, such as music, movement, and world languages, are evenly scheduled throughout the middle of the day to the extent possible.