Educational and cognitive research provides some important insights into how to improve learning and memory.  The key theme is that learning can be enhanced through driving recall by working with taught information in new forms (summarizing, associating, testing) repeatedly over time.  Passively hearing a lesson once is not effective (even with review at the end) in promoting learning of material.  There are several ways to apply this idea to teaching the Bible to children:

• Have the students explain what they’ve learned to someone else in the class at the end of the class or as a review from the previous class.  This form of recall helps retention of the material.  One way to structure this is to pair younger and older children.  Have the younger child explain what they learned first because they’re less likely to have mastered the material.  The older of the two can then fill in the gaps by explaining the lesson in more detail
• To improve learning in older kids, have them take notes on key ideas, organize information to compare and contrast it and create associations with what they already know and writing practice questions (source)
• Test the class on what they learned.  This drives recall better than reviewing the material again in the same lesson (see testing to take tests)
• Repeating material over time (many weeks) is critical to driving recall, so summarizing key points from previous weeks rather than immediately starting on to new material will reinforce what was learned and move it into long term memory (review research on recall)
• Increase learning engagement/attention by finding something students can relate to in the lesson; even if the connection is trivial.  For example, a history story that illustrates someone’s trust in God through a trial will be more engaging if it’s setting is from the children’s hometown rather than somewhere they’ve never heard of.  This would likely also apply to engagement with the teacher.  Find some similarity between you and each student to make a connection with them and improve their intake of the material (read more about stories we relate to)
• Sleep, exercise, not multi-tasking and separating older boys and girls also helps improve learning, but these generally can’t be controlled in a classroom

You can find a summary of additional research here