These students cannot listen precisely to sounds and words. They can be helped immensely by a professional speech and language clinician in the public schools or in a private clinical setting. It is essential to be sure that the specialist has appropriate training. A good place to check credentials is through your state, provincial, or international Learning Disabilities Association. You will find phone numbers and addresses on the Internet.
Parents can help at home, too.
They can check in a mirror as well. As many as you can think of. Read simple poems and ask the children to fill in the rhyming word that fits. The beloved Dr. Seuss books, in every public library, are excellent for listening practice, too. Ask the children to count the number of words you say in a sentence, starting with just two words, then extending the length.