Nehemiah 8:7 & 8
"The Levites - Jeshua, Bani, Sherebiah, Jamin, Akkub, Shabbethai, Hodiah, Masseiah, Kelita, Azariah, Jozabad, Hanan and Pelaiah - instructed the people in the Law while the people were standing there. They read from the Book of the Law of God, making it clear and giving the meaning so that the people could understand what was being read." NIV translation
So, we see how this great Bible study took place. Ezra would read from the Law and these men were stationed throughout the crowd. They would answer questions that those around them had concerning the words that were read. This is a part that is missing from many of the worship services of bodies of believers as it has gotten to the point where a speaker reads a tiny bit of God's Word and then adds a bunch of their own words. There is very little interaction to see if the people have any questions; it is just assumed that the speaker has covered all of the questions that could be raised. This is why most of the teaching is ineffective as many people put in their time and leave not understanding what they have heard.