The map in figure 2 reflects the closure of schools at ISCED levels 1 to 3 indicating the expected date of opening where they are closed. Schools are considered closed if pupils and students may not attend them, and receive instruction from home. This does not change if only the children of key or essential workers are welcomed on the premises. In Czechia, primary schools (ISCED 1) opened their doors from 25 May for groups of not more than 15 pupils. However, the final decision to open the school lies with the school head, and parents may opt to keep their children home. Upper secondary schools (ISCED 3) opened their doors only for students in their final grade on 11 May in order to allow them to take the national exam. In Denmark, primary and upper secondary schools opened their doors on 15 April to students in their final year, on condition that the schools can ensure social distancing and hygiene standards. Schools remain closed for all other students until further notice. The map indicates the most common date in Germany, as some variation exists. In Luxembourg and Austria, upper secondary schools opened only for final-year students on 4 May. In Finland, the first three grades of primary school remain open, but whenever possible, children should stay home and use distance learning.