Okay kiddo, developmental psychology is like when you watch your little brother or sister grow up and learn new things over time. People who study developmental psychology write things down in a special book called a journal.
In the journal, they write about how kids and teenagers grow and learn. They look at things like how they talk, think, and behave. They also write about how parents and teachers can help kids grow and learn in the best way possible.
The people who write in the journal are like detectives. They look for clues in how kids grow and change. They might watch how babies move around, listen to how kids talk, or see how teenagers behave. They take all the clues they find and write them in the journal so other people can learn too.
So, developmental psychology is all about watching kids grow and learn, and writing it down in a journal so other people can learn from it too!