A friend and colleague of mine, Dan Kassis, wrote an article on adding depth to Sunday School lessons by using commentaries. As he notes, all of LifeWay’s adult ongoing Bible study curriculum have leader guides that contain commentary, but there are other advanced options if you want to know more and add depth to your understanding of Scripture. I am now carrying some commentaries on my iPad, and I have numerous sets in my personal library. I like to read the Bible first, do my own careful study, then consult a good commentary or two to add to my depth of understanding and to check my accuracy. Invest in a good commentary set and it will pay both you and your learners big dividends.