At the end of the First World War, Koch returned to Berlin and resumed teacher training in the spring of 1919, which he completed in autumn 1920 with the first state examination.
Besides this training as a public school teacher, he also began studying pedagogy and medicine at the Royal Friedrich Wilhelm University (Königlichen Friedrich-Wilhelms-Universität).
Koch tried to immediately realize his reformist ideas of a "new upbringing" and was active in the Association of Resolute School Reformers [de] (Bund Entschiedener Schulreformer) until 1923.
Not to mention bathing.For health reasons, Koch promoted daily body cleaning and dental hygiene, which was not a matter of course at the time.
The aim was to encourage the girls to practice basic hygiene every day – with visible success: clean, healthy and happy children.
It is inconceivable how the gymnast can find his way around the unusually complicated structure of the human body if he is not given the opportunity of constant observation of detail, as is the case with the doctor and the artist.Koch's goal was now to develop a modern general physical and posture school (Körper- und Haltungsschule), with open style dance gymnastics according to Mary Wigman.
Curiously, from this school transfer, it would be the first time Koch would come into contact with the Freikörperkultur (free body culture) social movement, that had existed in Berlin since shortly after 1900.
Some of the parents of the school's pupils had formed a "friendship society" to do something for their body fitness in their free time; there were no formal statutes to this association.
At the end of 1922, Koch brought the gymnastics exercises into his school lessons with the children initially clothed wearing swimming trunks.
In addition to gymnastics, the school program also included hydrotherapy, high-intensity heliotherapy, medical examinations and care, discussions on all problems and further education.
Koch described the process as follows: It was a significant step for the German Freikörperkultur (free body culture) movement of that time period.
[3] Koch also presided over a busy publishing program and edited the nudist journal Körperbildung/Nacktkultur (Physical Education/Nude Culture) 1928–1932, which, unlike other Freikörperkultur magazines reaching the public, stressed the idea of nudism as an indoor, classroom activity.
Several judicial processes had been brought against Koch, set in motion by uptight moral apostles, but none resulted in a conviction (in the negative sense) or the closure of schools.
Koch did not let himself be deterred, he continued to work illegally, founded two new institutes one after the other under different names and helped many Jews and other victims of Nazi persecution.
During the Second World War, Koch was officially called up for military service as head of sports for the wounded and the follow-up treatment of the disabled in Castle Marquardt [de] near Berlin.
After 1945, Koch immediately started building up a new institute, which the Senate of Berlin soon after recognized as an "open school facility" (Freie Schuleinrichtung).
During the Adenauer era, the DFK association tended to bow to public pressure, as the promotion of naturism was still considered by some as harmful to young people and immoral.
In 2003 Irmgard Koch withdrew from the institute and moved to her daughter in Sanitz (near Bad Doberan on the Baltic Sea coast).
In its beginnings, following a fashion trend of the late imperial era, this social movement was partly shaped by misinterpreted Darwinian ideas.
[you]), Koch stood – based on the ideals of the Age of Enlightenment – as a motto-giver for the tendency towards egalitarian self-claims of undressed group life.