We live in a universe with 3 big spatial dimensions (left/right, front/back, and up/down). They are often labelled on a graph as x, y, and z. In his theory of special relativity, Albert Einstein showed that time is a 4th dimension that can be combined with space to form spacetime. However, time is special from space in that it only has one direction. As far as we know, you cannot go back in time. This is called the Arrow of Time problem.
The question: why does time only move forward and not backward?
First Place: The Flow of Time by Josh Arnold, Williamsville East High School, Williamsville, NY
Second Place: The 4th Dimension by Benjamin Zakes, Medina High School, Medina, NY