Ok, let's pretend that we want to make a big city with lots of streets and buildings. But we don't want it to be too messy, it has to be organized and easy to move around. That's where the Commissioner's Plan of 1811 comes in.
This plan was created by some very smart people called Commissioners. The Commissioners decided to make the city in a grid pattern, which means that all the streets and blocks are arranged in neat rows and columns just like on graph paper.
They made the blocks nice and big so that lots of people could live and work there. Each block was also divided into smaller lots that people could buy and build their own buildings on.
Oh, and they also made some very special and big streets called avenues. These avenues were really wide and ran north to south throughout the city. They were made like this so that it would be easy for people and things like carriages and horses to move around without bumping into each other.
So, that's the Commissioner's Plan of 1811 - a smart idea made by some smart people to make the city easy to navigate and organized. Now you know why the streets in New York City are so easy to move around in!