Famous St. Petersburg teacher and one of the authors of geometry textbooks shares his experience of teaching mathematics at school. The book discusses ways to develop a student, the educational role of mathematics, a system of problems in geometry, compiling didactic materials and tests, using a computer in a school course, etc. The author gives specific methodological solutions to some of these issues. The book gives original problems and methods of solution. The book is addressed to teachers of mathematics, methodologists, as well as everyone who is interested in educational problems.