The education system in the Netherlands has several stages. Preschool is optional for children ages 3-4 and focuses on play-based learning. Elementary school is compulsory for ages 4-12 and students are grouped by age or knowledge. Secondary education has three paths - pre-vocational education focused on technology and careers; senior general secondary education; and pre-university education preparing students for higher education. Higher education includes universities of applied sciences and research universities offering bachelor's and master's degrees, as well as an Open University for adult learners. The Netherlands' education system emphasizes more choices for students, attention to individual abilities, practical work experience, and schooling through age 18.