Effective computer support for courses in drawing, computer science and geometry is demonstrated based on the freely distributed KOMPAS-3D LT system. General information and work with the system are described, and the basic concepts of three-dimensional modeling of geometric objects are given. The creation of three-dimensional models of parts and their projections, drawing dimensions, depicting threaded connections, and creating assemblies are discussed in detail. The possibilities of using KOMPAS-3D LT in solving problems of graphical information processing and geometric three-dimensional modeling are shown. Examples are given of solving planimetric problems and creating 3D models of elementary geometric bodies. The appendices contain draft and test assignments. The DVD contains distributions of the programs in question and dozens of options for practical tasks on all topics mentioned in the book. For students and teachers of universities and colleges, students and teachers of secondary schools, directors of advanced training courses.