The book contains tasks and practical exercises of varying complexity - from simple and funny to olympiad. They are aimed primarily at developing the skills of meaningful and effective work with information. The necessary theory is presented in simple language, accompanied by author's drawings. At the end of the book, answers and explanations for the tasks are given. Reading does not require special knowledge of computer science, basic knowledge of mathematics at the level of the 6th grade of the school is enough. Some of the tasks are solved in the mind, others require paper and a pen. For tasks performed on a computer, an electronic archive of working materials is available on the publisher's website. The book will help interest children in computer science, prepare them for mastering the high school curriculum and participating in olympiads and competitions.