Bijoy

Are the following sentences correct, gramatically? If yes, is there any difference in meaning between them? 1. Teacher spoke to the concerned parents 2. Teacher spoke to the parents concerned

Hi Mr. John, I am not a language expert, but would like to comment on your query. I feel 3 and 4 are incorrect. Or at least they sound so. To me, 2-2 and 5 sound gramatically perfect, while 1 and 2 sound ok, but too casual. Hope this helps