Why is "tabla" defined after a preposition, unlike "pe masă" and the sort? It's because it has an adjective, am I right?
Yes, without the adjective it would be 'la tablă'
Why is it la and not pe in this sentence?
It should be 'PE tablă'. 'LA tablă' is the translation for 'AT the blackboard'.
Would it be possible to change the word order a little bit here?
I wrote: "Eu scriu frumos la tablă neagră cu cretă albă." Is that not in your database or is it just plain wrong?
Why "cu cretă albă"? There is another example with "cu creta roșie", where "creta" is defined. I thought, the rule is "cu" + "an instrument" - noun is with definite article.
I guess it's because it's "with white chalk", and not "with the white chalk". In the english sentence, white chalk is not defined, that's why it is not defined too in Romanian