Sporadically is the adverb: it tells you HOW something happens — now and then, scattered through time, with no pattern you can count on. 'He works sporadically' means he works some days and not others, and you could not draw up a timetable from it. Because it is an adverb, it attaches to a verb, and that is exactly where students need it: the adjective 'sporadic' describes a thing ('sporadic rain'), while 'sporadically' describes an action ('it rained sporadically'). Same idea, different job in the sentence. Watch where it sits. It usually goes after the verb — 'she posts sporadically', 'the machine beeped sporadically' — or at the end of the clause. You can also put it before a past participle: 'the road is sporadically maintained'. Keep the real meaning in mind: not 'rarely', but 'unevenly, in scattered bursts'. Someone who goes to the gym sporadically might go four times one week and not at all for a month. The total could be quite high; what is missing is regularity. There is often a small note of disappointment in it — sporadic effort is effort that doesn't add up. It belongs to careful, slightly formal English: reports, news, academic writing. In everyday chat people say 'on and off' or 'now and then' instead.