--- title: "Make a sundial and mark the hours" published: "2026-10-15" updated: "2026-10-15" author: "Dad Field Manual editors (drafted with AI help)" time: "1 hr, spread over a sunny day" cost: "$0" ages: "6 and up" where: "A deck rail, a stump, a flat patio stone or a level patch of yard that gets sun all day and where the dial can stay put." topics: ["classic-skills","outdoors"] print: "https://dadfieldmanual.com/print?p=make-a-sundial" url: "https://dadfieldmanual.com/plans/make-a-sundial/" --- # Make a sundial and mark the hours > A board and a slanted pointer aimed north. Mark an hour line each time the clock strikes, and by evening its shadow tells the time. ## What you need - A flat board or stiff cardboard about 15 inches square (have) - A piece of stiff cardboard for the pointer (have) - A protractor, ruler, marker, scissors and tape or glue (have) - A phone with a compass app and a map that shows your latitude (have) - A clock or phone to mark the hours (have) - A couple of rocks or bricks to hold the board down (free) ## Before you start - **Never look at the sun,** not even with sunglasses. Look at the shadow on the board, never the sky. - **Grown-ups handle the scissors or saw** for the pointer. - **Hats and sunscreen** if you'll be out checking the dial all day. ## Steps 1. **Find your latitude and north** (Dad) Look up your latitude on a phone map: a number of degrees north, like 36. Then find north with the phone compass, or the night before sight the North Star the way the 1911 book does (see [find the North Star](/plans/dipper-and-north-star/)). Mark north on the deck or ground with tape or a stick. 2. **Cut the pointer** (Dad shows, Kid copies) The pointer is called a gnomon. Cut a cardboard triangle with a square corner, and use the protractor to make the angle at its tip equal to your latitude. The long sloped edge is what casts the shadow. 3. **Build and aim the dial** (Kid) Draw a line down the middle of the board: that's the noon line. Tape or glue the pointer upright along it, tip at the south end, so the sloped edge rises toward the north. Set the board level, noon line pointing north, and weigh it down. From now on, don't move it. 4. **Mark the hours by the clock** (Kid) Every hour, on the hour, draw a line along the edge of the shadow and write the hour. While daylight saving time is on (in most of the US, until the first Sunday in November), write one hour less than the clock says: at 2:00 on the clock, write 1. Then the dial keeps standard time all year. 5. **Read it the next day** (Together) Next sunny day, ask, “What time does the sundial say?” Then check the clock. In daylight saving time, add an hour to the dial's answer. How close did it get? 6. **Check it again in a month** (Together) Leave it out, or put it back in the same spot aimed the same way. In a month, check it against the clock again. A few minutes off is normal: sun time drifts against clock time through the year. ## If it stalls - If clouds roll in partway through, mark what you can and finish the hours on the next sunny day. Don't move the board. - If the shadow is fuzzy, read the middle of the fuzzy edge, and trace with a ruler. - If the dial reads an hour off, check whether daylight saving time is on. ## Variations - **Ages 6–7:** Skip the latitude angle: stand a pencil straight up in a lump of clay on a paper plate, and mark the hours by the clock. It works best the same week you mark it. - **Ages 8–11:** The full plan. Try the [shadow-stick](/plans/shadow-stick/) to find north, then compare it with the phone compass. - **Ages 12+:** Use the hour-line angles on NASA's sundial page to draw the lines with a protractor before the sun does it, then see how well they match. Compare with the [watch compass](/plans/watch-compass/), which runs the same idea backward. - **Cloudy:** You need a clear shadow. Wait for a sunny day. - **Windy:** Weigh the board down well, or tape it to the deck. ## Sources - **1911 scouting handbook, pp. 58–59.** The 1911 book describes a scout's sundial, or hunter's clock: a smooth board about 15 inches across, set on a level post or stump in the open, with its twelve o'clock line aimed north by the North Star and a pointer set to aim at the North Star, at the same angle as the latitude. It says the dial is roughly correct for that latitude and the pointer angle must change for each latitude. (checked 2026-10-15) - **Pointer angle, hour lines and sun time vs. clock time.** NASA's archived sundial page says a sundial works at all times of year if its pointer slants toward the celestial pole, at an angle to the base equal to your latitude, and must point north; it lists unequal hour-line angles for a flat dial; and it says the dial is an hour off during daylight saving time, differs from clock time because of time zones, and has a yearly variation (the equation of time) of up to about 15 minutes. (checked 2026-10-15) - **Never look at the sun.** NASA says it is not safe to look directly at the Sun without specialized solar eye protection, and that regular sunglasses, however dark, are not safe for viewing the Sun. (checked 2026-10-15) - **Daylight saving time dates.** NASA gives the US rule: daylight saving time begins at 2 a.m. on the second Sunday of March and ends at 2 a.m. on the first Sunday of November. (checked 2026-10-15)