Understanding "פסיק רישא דלא ניחא ליה" (inevitable results from one's permissible action whereby one receives no benefit from).
Ear Plugs, Examples of Strengthening an Item on Shabbos, Hairspray, Stretching Shoes, etc.
Understanding the Difference Between the Melacha of Kotzair-קוֹצֵר (Reaping) and Gozez-גּוֹזֵז (Shearing);
Breaking up words on the cake (not letters); eating chocolates with letters, alphabet cereal, etc.