Feedback is an important component of interactive learning software. A conclusion from cognitive learning theory is that good software must give the learner more information about what he did. Following the ideas of constructivist learning theory the user should be in control of both the time and the level of feedback he receives. At the same time the feedback system must identify and review different possible solution strategies in an open learning environment. The interactive geometry software Cinderella offers an easy-to-use programming interface. It can be used to implement application specific feedback by the author of learning units. In this paper we present two exemplary learning units implementing two kinds of interactive feedback: feedback on demand and immediate feedback. The presented units come from discrete mathematics and from the theory of line reflections and congruencies in geometry. The units are implemented in a process-oriented design. Various directly given or hidden hints help the students to understand the mathematical principles behind the given problems. Our tools analyses the student's solution processes automatically and generates additional feedback on demand. The second learning environment can also be used in conjunction with recording of user actions. This allows additional feedback given later by the teacher whenever the automatic feedback system fails in analyzing the users' learning processes. First experiences using the units in teaching are presented. The papers in this number are extended versions of the presentations given at the Second Computer Algebra and Dynamic Geometry Systems in Mathematics Education (CADGME) conference at the University of Linz, Austria, in July 2009. (Orig./DIPF/Hah).