Portuguese is the primary language of instruction in all Mozambican schools. All Mozambicans are required by law to attend school through the primary level; however, a lot of children in Mozambique do not go to primary school because they have to work for their families' subsistence farms for a living. In 2007, one million children still did not go to school, most of them from poor rural families, and almost half of all teachers in Mozambique were still unqualified. Girls' enrolment increased from 3 million in 2002 to 4.1 million in 2006 while the completion rate increased from 31,000 to 90,000, which testified a very poor completion rate.