Klaus Ruppersberg -born in Cologne- has got 24 years of experience of teaching chemistry and biology at different schools and to different types of pupils. Since 2014, he is based at the University of Kiel/ Germany (IPN - dept. chemical education/ Ilka Parchmann). His main interests are the teaching and learning of complex chemical knowledge and the development of demonstrative and safe experiments. Currently he is working on a special mechanism of a detection reaction for lactose, i.e. the Woehlk reaction.