Anyway, we do not know why these tablets were discarded. Who knows, the school's caretaker may have just cleared the lost & found in his office at the end of a semester. But it is most fascinating that they open a window to the past because they still bear the last notes that were carved into the wax surfaces. These are just being examined, transcribed and translated. Some of them speak of the battle of Helsingborg which was fought between Danish and Hanseatic fleets in 1362 (which is why we know they must have been thrown away after this date).
A tablet's frame was usually made of beech wood (German: Buche, hence the word Buch, which means book). You could erase a text by warming the broader end of the stilus, the writing implement, and smoothen the bees wax surface to write anew. These medieval communicators were not only used by students at school but also to send messages. And I find it intriguing that they had the same size as modern smartphones today.
Well, good design is timeless!