Morphemics and Word Formation
What to master
Morphemics studies meaningful parts of words: root, prefix, suffix, ending and postfix (including -ся/-сь). Word formation studies how new words are built from producing stems. You must distinguish derivational morphemes from inflectional ones, identify the producing word, and recognize the main ways of formation: prefixal, suffixal, prefix-suffixal, zero suffixation, addition (including abbreviation) and transition from one part of speech to another. A derivational chain shows which word is primary and which is derived.
Traps
Do not confuse a zero ending with no ending, or a postfix with an ending. -ся/-сь is a postfix, not an ending. The status of -ть/-чь in the infinitive depends on your textbook’s convention, so follow the analysis taught in your course. Prefixes can look like prepositions; endings can look like suffixes. Historical morphology can mislead: synchronically, a word may no longer divide as it did historically. Always compare the word with its nearest motivating word.
Worked example
Пришкольный is formed from школа by при- + -н- (prefix-suffixal): при-школь-н-ый. Выход is zero-suffixal from выходить: вы- + -ход- + zero suffix. The producing stem is the verb, and the zero suffix creates a noun. Rule of thumb: find the closest simpler word that explains both meaning and form, then compare stems.
Rule of thumb
Determine the part of speech first, then the producing word; this prevents false division into morphemes.