Archimedes was an ancient Greek scientist who lived a long time ago in a place called Sicily. He was a brilliant mathematician and scientist, and he made some very important discoveries that are still being talked about today! He was most famous for coming up with an idea called the "Archimedes Principle." This principle states that if you put something in water it will float if the water pushes up against it with a force equal to the object’s weight. This idea changed the world and helped people sail ships, build bigger boats, and understand why some things float while others sink. He also designed the first machine that could lift heavy objects with a lever and is credited with inventing the first tortoise-shell method of calculating long numbers. So, even though he has been dead for a long time, his discoveries still help us today!