This educational site quotes from A Social History of the Third Reich by Richard Grunberger, among others.
A detailed history of the "Education in Nazi Germany" that includes images, quotations and the main events. GCSE Modern World History - Nazi Germany. A-level - Life in Nazi Germany, 1933–1945. Last updated: 9th May 2022
Bernhard Rust introduced a Nazi National Curriculum. Considerable emphasis was placed on physical training. Boxing was made compulsory in upper schools and PT became an examination subject for grammar-school entry as well as for the school-leaving certificate. Persistently unsatisfactory performance at PT constituted grounds for expulsion from school and for debarment from further studies. In 1936 timetable allocation of PT periods was increased from two to three. Two years later it was increased to five periods. All teachers below the age of fifty were pressed into compulsory PT courses. (41)
Rust also establishment of élite schools called Nationalpolitische Erziehungsanstalten (Napolas). Selection for entry included racial origins, physical fitness and membership of the Hitler Youth. These schools, run by the Schutzstaffel (SS), had the task of training the next generation of high-ranking people in the Nazi Party and the German Army. (42) The syllabus was that of ordinary grammar schools with political inculcation in place of religious instruction and a tremendous emphasis on such sports as boxing, war games, rowing, sailing, gliding, shooting and riding motor-cycles. Only two out of the thirty-nine Napolas constructed over the next few years catered for girls. (43)
Other cites in that page pointed to how Hitler actually inherited a very conservative educational system, meaning that what the Nazis did was to get rid of the grammar Nazis and concentrate more in physical activities (meaning more future soldiers) that were more important for the Reich.
And even if the Germans noticed, they could not do much about the degradation of items like grammar.
Teachers encouraged members of the Hitler Youth to inform on their parents. For example, they set essays entitled “What does your family talk about at home?” According to one source: “Parents… were alarmed by the gradual brutalization of manners,** impoverishment of vocabulary** and rejection of traditional values… Their children became strangers, contemptuous of monarchy or religion, and perpetually barking and shouting like pint-sized Prussian sergeant-majors.” (31)
Bold added.