Okay kiddo, do you know what a review is? It's when you think about something you did and talk about what went well and what could be done better next time.
An after action review, or AAR for short, is when a group of people get together after they did something important, like a project or an event, to talk about how it went.
During the AAR, everyone talks about what they did and what they learned. They also discuss what went well and what they could improve on next time.
The AAR is like a game plan for the next time something important is done. It helps people remember what worked and what didn't so they can do better next time.
Does that help you understand what an after action review is, kiddo?