Basic principles of Russian orthography. Non-alphabetic vowels in the root of a word. Spelling of prefixes. Spelling of vowels after hisses and ts. Spelling of verbs. Difficult cases of formation of verb forms. Spelling n and nn in adjectives, participles and words derived from them. Spelling of prepositions, conjunctions, particles. Spelling not with different parts of speech. Use of lowercase and uppercase letters. Defense of own projects