This sentence is what is called خبر in Arabic grammar it is a basic predicate sentence and is marked by an indefinite adjective following a definite noun (a definite noun is one that has the أل prefix or a possessive suffix example the following sentence means "the dog is big" الكلب كبير to say "the big dog" one must write الكلب الكبير Another example of this form would be this sentence meaning "your house is old" بيتك قديم This is an example of possessive pronoun suffixes marking the definite form
Yes, it is wrong.
Remember those people who comment on sentences like الباب باب (The door is a door) and say that it is a Duo nonsense to teach us a silly sentence like that?
Now you know why you need to learn "The door is a door" thoroughly so you don't make mistakes like above.
For records, "The Jordanian teacher" = المعلم الاردني.
Hope this helps.
A bit harsh Aaron! Think of it this way, when you see the word 'ال', in English replace it with 'the'. So 'المعلم' is now 'the teacher' and start your sentence like that. المعلم ذكي becomes 'the teacher IS smart. معلم ذكي should be 'a smart teacher'. If you don't see the 'ال' , think of it as an 'a' or 'is'. So in this example: المعلم أردني 'the teacher' (is) Jordanian. In Ghaith's example about the dog: الكلب الكبير. The dog, the big (one) would be the same as saying 'the big dog'! Not an Arabic speaker at all, but hope it helps.