Create a Sundial

Construct a working sundial that tells the time by using the position of the Sun. The sundial uses a gnomon (a tilted stick or triangle) that casts a shadow on a marked surface. By aligning the gnomon to your local latitude and facing it true south, you can measure the apparent solar time as the Earth rotates.

• See links below for methods on making and using a sundial.

Make a Sundial STEM Activity - Mission Viejo, CA:

Make your own Sundial! | Nanogirl's Lab | STEM activities for kids - Nanogirl - STEM activities for kids:

📄 It’s About Time….To Make A Sundial! - Megan Arnett: https://www.sciencebuddies.org/stem-activities/its-about-timeto-make-a-sundial

📄 Create a Sundial - Gaffney, L., and Harper, A: https://cms.qut.edu.au/__data/assets/pdf_file/0017/24092/create-sundial-teacher-worksheet.pdf

• Build a larger outdoor sundial using wood or metal.
• Compare the sundial time with a clock throughout the day to calculate solar time differences.
• Mark additional half-hour or quarter-hour lines for more accuracy.

• Use scissors safely when cutting cardboard.
• Avoid looking directly at the Sun while aligning your sundial.
• Set up in a stable outdoor area free from wind or tripping hazards.
• If used long-term outdoors, protect with waterproof coating or laminate.

• Why is latitude important when building a sundial? (The gnomon’s angle must match the location’s latitude so it aligns with Earth’s rotational axis.)
• Why does the sundial need to face true south rather than magnetic south? (Magnetic south differs from the Earth’s rotational axis, which affects shadow accuracy.)
• How does the Sun’s movement across the sky create the shadow that tells time? (The Sun’s apparent motion due to Earth’s rotation changes the shadow’s direction and length.)
• Why might your sundial show a slightly different time from a clock? (Clocks show mean time, while sundials show apparent solar time, affected by the equation of time and longitude differences.)
• What can this experiment teach us about Earth’s rotation and the position of the Sun? (It demonstrates how timekeeping and celestial movement are linked through predictable solar motion.)