This article describes how kindergarten scientists at Caldwell Heights Elementary School in Round Rock, Texas created what they named a "Light Circle" using their classroom's south-facing window, its windowsill, and a small round mirror. The tilt of the Earth and the latitude of one's location combine to determine if the Sun ever shines into classroom windows. For schools located north of the Tropic of Cancer (latitude 23.5 degrees north of the equator), the Sun shines into a south-facing window all day long, clouds notwithstanding. After realizing they had a south-facing window, the class decided to glue a one-inch round mirror to the windowsill to watch what might happen. Right away, the children noticed the reflection of the Sun on the ceiling. They marveled that their Light Circle traveled across the ceiling each sunny day. They connected this to the movement of the Sun across the sky from east to west. As the autumn months passed, the children noticed the location of the Light Circle path changed. It got farther and farther away from the window. When they returned to school after the holidays, the children noticed the path began to move back toward the window. Regardless of whether schools are open or not, this activity could also be implemented at home. Teachers can encourage each child's family to find a south-facing window and affix a small mirror to the windowsill. That's it. Although space systems do not enter the Next Generation Science Standards (NGSS) sequence until first grade, this activity can generate curiosity and pave the way for a deeper understanding before the kindergartners move on up.