In the sentence below:

Exercises, which were corrected by the teacher on the blackboard, made a lot of mistakes.

and it can be rewritten:

Exercises,corrected by the teacher on the blackboard,made a lot of mistate.

However,I read in a book, I see they write:

Exercises,to be corrected by the teacher on the blackboard,made a lot of mistake.

Could you tell me differences between 1(2) sentence(s) above and the last sentence.

Thanks!