This root hides a beautiful tension: to do something a second time is to repeat it (לשנות, to review), but to make something other than it was is to change it (לשנות, to change). Same letters, one idea of "a second state". From it grow the student's review, the Mishna (the "repeated" oral law), what is different (שונה), the act of change (שינוי), and the strange (משונה, literally "changed"). Even the year, שָׁנָה, the cycle that returns, is its cousin. Every word here is verified against pealim, niqqud included.
The same root runs through the verb system. Each binyan is a voice: it bends the one idea into active, passive, causative or reciprocal. Tap to hear.
Notice the labour split. Pa'al keeps the plain sense of "do a second time" (review); pi'el is causative-transitive, "make it other" (change something); hitpa'el turns that change back on the subject, "become other" (change oneself). The same root runs from a student's revision to a thing transforming itself, just by switching binyan.
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.