The paper discusses the issue of school knowledge from the point of view of scientific knowledge, ignorance and faulty knowledge. The starting point is that neither school nor curricula pay attention to what knowledge is, what types of knowledge there are, and what kind of relationship exists between knowledge, ignorance and faulty knowledge. The first part offers an answer to the question what knowledge is. In the second part presented are some theoretical viewpoints on knowledge: gnoseological, sociological and psychological. The third part deals with the notions of ignorance and "faulty" knowledge. Pointed out are some forms of mystical ignorance. The forms of faulty knowledge are: erroneous notions, prejudices, illusions. In the final part, the author considers their relationship in school education. The starting point is that ignorance is a predecessor of any knowledge. The difference between knowledge, ignorance and faulty knowledge exists in every system of school education, but differs in extent and mode when it comes to nature, society, man and art. The author maintains that school should not be defined as an absolute carrier of knowledge, or the system of foolproof knowledge that the student should acquire uncritically. Instead of absolute confidence in scientific knowledge, the paper concludes with suggesting the option of an "elastic form" of school knowledge. This is a type of knowledge which, in its programme, counts on both ignorance and faulty knowledge and their differing roles in studying and real life of students.