I know for some librarians the thought of student self check out is horrifying, but I have found it to be liberating. I implemented self check out at the beginning of the year. I have two computers stationed at the circulation desk. One is turned around to face the front and the other is to the side. The computer that faces the back of the desk has a separate number pad device so that students may type in their Destiny patron number and reach the scanner even if no one is behind the desk. During the orientation visits for each class I gave a short lesson to the students as they checked out their first book. Yes, I still find myself teaching students even though we are nearing the end of the first semester, but this is happening less and less. Usually the other students in line will teach someone that is struggling. I have also taught students how to put books on hold, renew books and even check in their own books.
I do not have a library aide, but I do have two student helpers during most of the school day. Often I am busy teaching a class, helping students locate books or some other administrative task. It is to my benefit for students to know how to do this for themselves. It is also important for students to learn these skills. I rarely have to stop and show a student how to search for a book because they know that they are welcome to use the circulation desk computers. They have learned the operations of the library and by helping, the library becomes "theirs" not "mine".
I have heard the argument that middle school students can not be trusted wth this responsibility because they may intentionally check out a book to another student or some other malicious act. To my knowledge I have not had anyone do anything intentionally. I have limited the tasks for these computers to check in, check out, place hold, delete hold, and renew. Students must still come to me for paying for a lost book, reactivating a restricted status, report features, etc.
If you are willing, give self check out a try. You will not regret it.