Here is a book you will find useful, and you can adapt it to suit the level of your students. Citizenship Now! - Karen Hilgeman, Kristin Sherman, et al. It's available on Amazon. It also has a DVD, with simulated interviews, which your students will find very interesting to watch. It also has a lot of English practice, exercises.
There is a lot on the internet too. Also, go to www.uscis.gov to find out more about the process. They also have practice questions.
Have students make flashcards together of all the 100 questions.
I'll send you some more information later in a personal mail.
I found preparing students for this important test very rewarding and I ended up taking the test and getting my citizenship while I was teaching them! Good luck!
My wife took it last year - 100 questions in the pool, 10 are asked.
An 80 year old Venezuelan lady I know took the test, in English, and she was doing very well until they got to the question: “Who is the Commander in Chief?”
She rolled her eyes and said, “I can’t remember his name...but he’s a real jerk.”
She passed the test and was sworn in!
A few years ago I had a Japanese co-worker who was studying for the citizenship test. She showed me the questions. Most native born Americans could not pass it. Can you name the original 13 states? Can you name all of your elected representatives?