As such, most primary schools (preparatory grade to fourth grade) have a uniform. In recent years, school uniforms have become more common for middle schools, and even some high schools have introduced them. School uniforms are more common in urban areas. School uniforms are not without controversy. Critics argue that some parents cannot afford them, that some schools send children at home or lower their grades if they do not comply (this practice has been ruled illegal), or that there are illicit agreements between school administration and clothes producers. The 2018 regulations state explicitly that children cannot be punished or denied access to education for not wearing a uniform.