Problem solving and problem understanding are interwoven. Often at the beginning of a project, engineers' knowledge is insufficient with regard to the posed problems. The correct specification of a task may depend on its solution, which is why the conventional sequence of specification and solution cannot be maintained. Methods are needed to deal with 'imprecisely posed problems', by which the solution process will be adapted to the essential problem structures only. We present procedures to detect these essential structures and to acquire problem solving skills from the solution process itself.