"The Story of X" is a cheesy little story I use to teach my students the simplicity of solving one-step equations. I have found that if the steps are done in a story the students remember them much easier. I would highly suggest this for first time learners in middle school as well as low ability learners in ninth grade.
You will need to supplement with addition/subtraction and multiplication/division practice sheets.
X has a love for ice cream sundaes which gets him into trouble. His friends "subtract and add" themselves out of his house when they hear the police come!
After X gets caught too many times he gets put in jail where his wife and he use division and multiplication to try to get back on their feet.
If this works well for you feel free to try my favorite notes "Who's Lonely/Who's the Big Guy" which looks into solving two and three step equations with guiding questions.