This presentation doesn't require any special knowledge in computer science and is based on a two-years-long teaching experience in intermediate classes of High School. The aim of the talk is to introduce to computer science, starting from the fact that teaching and learning of programming is difficult, particularly for a generation of so-called "digital natives". The route starts from the algorithm represented by flowchart (as long as the number of blocks does not exceed ten) and pseudocode to arrive early to Python code. The innovation of this proposal is to combine educationally Leap, a special type of pseudocode, and Python. Leap is available online and can be used to write pseudocode, which can also be executed. In addition, you can run a pseudo-program step by step and display in a trace table the sequence of instructions and the value of the variables used. This talk will highlight concrete examples of logic and mathematics how to move from the problem to the algorithm expressed in Leap and finally to the Python program . The speaker wants to show once again that Python is very well suited for teaching and Leap, for its part, can be an other useful tool in the teacher's and student's toolbox.