Of Alexandria was a very smart person who lived a long time ago. He was so smart that people still talk about him today!
Of Alexandria was really good at doing all sorts of mathematical and scientific things. He was especially good at figuring out how to measure things like the size of the earth, and how to figure out how much water was in a container using a really cool trick that involved balancing the container on a see-saw.
Of Alexandria also wrote a lot of books about what he learned, and some of them are still around today for people to read. He wrote about things like how to build machines that could do all sorts of tasks, and ways to measure things like the distance between the stars.
Of Alexandria was so good at what he did that people started calling him the "father of all scientists". Even though he was really smart, he wanted other people to learn too! That's why he started a school in a place called Alexandria, which was in Egypt. Many students came from all over the world to learn from him and become smart too.
Of Alexandria was an amazing person who did a lot of amazing things, and even though he lived a really long time ago, we still remember how amazing he was today!