Memorizing someone else’s words or reading directly off of a script are fine for the theater, not a Sunday School classroom. Instead, a better way is to learn how to make the lesson your own.
The lesson should be a clear guide for you to follow, but you’ve got to put things into your own words and let your own personality shine through as well. The kids don’t need a robot teacher, they need a real person who connects to the lesson and helps them understand the lesson and apply it to their own lives.