Problem solving is a critical competency for modern world and also an effective way of learning. Education should not only transfer domain-specific knowledge to students, but also prepare them to solve real-life problems - to apply knowledge from one or several domains within specific situation. Problem solving as teaching tool is known for a long time, but our aim is to enhance it by suggesting knowledge tools for different stages of problem solving process. Knowledge tools involve students in the process of knowledge construction that contributes to understanding of subject and help students to organize and present their own knowledge. An overview of software, which help to apply the suggested knowledge tools, is presented as well. Finally we illustrate our approach with two examples of teaching school and university students.