Toddlers throw tantrums for all kinds of reasons, both logical and illogical. A fit could be thrown for the understandable reason that they’re simply tired at the end of a long day, or they could be fine one second and ultra-pissed that you dared to pour their milk into the green cup when you should have known they…
source https://offspring.lifehacker.com/how-to-avoid-transition-based-tantrums-1846363670