There is a special possibility to organize knowledge by using so-called mind maps. A structured presentation can help, to get an overview about a komplex issue and depict dependencies and komplex relationships. Futhermore it can be helpful in acquisition of knowledge and also at a presentation. There is an amount of such tools around the topic but they certainliy differ in regards to complexity and capacity. Very simple and free tools like Popplet are almost intuitive to handle and therefore particularly suitable for school. One of the most extensive tools is iThoughts. This app includes different standard shapes like herringbone pattern or horizontal or vertical alignement and all elements can be selected in a highly differentiated manner. Backgrounds, forms, colours, font and font size, different kinds of arrows and connection lines can be freely selected. Additional features like creation of tasks, dates or attachements are included. One special feature is the possibility to show or hide different layers, which can be useful especially at the presentation of a topic.