subsequently, this was replaced by examinations in more natural science subjects, and many schools have special subject weeks focusing on cross-disciplinary subjects, for example about the environment and nature. an internet portal has been established containing information for teachers teaching in this field. furthermore, for several years now the ministry of the environment has been running a competition for school children called "clean week", in which 5th and 7th graders compete to create

Make this proper case.
Subsequently, this was replaced by examinations in more natural science subjects, and many schools have special subject weeks focusing on cross-disciplinary subjects, for example about the environment and nature. an internet portal has been established containing information for teachers teaching in this field. Furthermore, for several years now the ministry of the environment has been running a competition for school children called "Clean week", in which 5th and 7th graders compete to create