Translation:I write beautifully with white chalk on the blackboard.
We have to remember that the use of prepositions is not the same in different languages... for example, where Romanian uses ”la”, the English translation is usually ”at” but it might as well be ”in”, ”to”, ”with”, ”towards” or yet another preposition, depending on the context.
Well, I am Romanian! I think I know what is the best way to write in Romanian! And PE- means on!