In its most basic form, a sundial is any device that can tell the time of day by the sun. Sundials have been used to tell time for eons, but today can be found in a more decorative form in your grandma’s petunia garden.

We made our sundial from a triangular slab of concrete over at the Leslie Spit, by placing the slap on a flat surface, aligning it with the sun at exactly noon, and marking its shadows on the half-hour as the sun moved across the sky.