well i can tell you this one, you take the correcting fluid (the white stuff), remove the label, very carefully not to rip it, then, you dust the glue of the label, so it won't stick back on, now you put the label back on in a way that there remains a 3mm crack between the end and beginning of it, then tape it over with duck tape (?), now you can remove or twist the label so..all you need to do is write all over your correcter.
i also have a better one, but i won't tell it here, since i know teachers/profesors use internet too ;)
if you wanna, send me PM.