I have a software product that might be useful for you and your students. It's called SpellQuizzer and it is designed to help students learn their spelling words. It could be used for
ESL learning as well though. You create word lists using the software and make sound recordings of the words using them in sentences. The student then uses the software to be quizzed on the words. It plays back the sound recordings and the student types in the words to have their spelling checked. I don't know if this will help you or not but you can take a look at it at
www.SpellQuizzer.com. There are video demonstrations of the software that give a good idea of how the software works.
At present I'm offering free licenses to teachers who contact me using an email address associated with an educational or government domain institution. You can request a free license.
Note: I hope the moderators won't consider this post to be "unsolicited spam" since I'm posting in response to a request for assistance and I'm offering the software free.
Dan