In the 1980’s a German psychologist, Kuno Beller, noticed that many children in kindergarten got sick, as a result of the emotional stress caused by the sudden separation from parents. In a set of experiments inspired by John Bowlby’s Attachment theory and Mary Ainswroth’s Strange Situation, Beller devised a transition model that allowed children to settle in kindergarten more peacefully. As a result, the number of sick kids dramatically decreased!