I've had some students recently that although they are older they still have skills under 18 months of age. I found myself looking more into their babbling and where they were at in their stage of babbling - (reduplicated, varigated, varigated with intonation, jargon, etc). I felt I needed to write everything down, they try to narrow down a few behaviors and toys that they like - because they have seen everything in my classroom! I hope to find new activities for these students this year. I hope this helps you in your journey in the world of babbling and very early developing skills.