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Interactive Science: The Human Sundial

By Genia Connell on October 11, 2012
  • Grades: 1–2, 3–5

I believe that the more actively engaged students are in their learning, the more lasting knowledge they will gain. So, a few years ago when I saw an experiment that called for students to learn about shadows by taping a straw to a piece of paper and taking their homemade sundial outside, I automatically thought, why would I use straws? I’ll turn my students into human sundials.

This experiment works well if you are studying the sun, light, or shadows; however, it is also a great way any time of year to get your students making predictions, collecting data, recording observations, and drawing conclusions.

The objective of this experiment is for students to learn how shadows are created and how they move and change in relationship to the sun’s position. Before the experiment begins, I pose the question, "How can you tell time without a watch when you're playing outside on a sunny day?" What follows is the day-long activity we do to discover the answer to that question.



  1. Start by checking the weather. This activity needs a day with full sunshine, so pinpoint a good, cloud-free day in advance.
  2. Choose a large area of pavement where your students can trace shadows. I use the blacktop portion of our playground.
  3. Copy the shadow observation form, the data collection chart, and the sundial sheet. I created my Sundial sheet with my school in mind, so you will need to adjust it to fit your environment.
  4. If you have a die cut machine, use that to cut out one silhouette for each boy and girl on black construction paper. If you do not have a die cut, hand cut them using this silhouette template.
  5. If you do not have enough flashlights and clipboards available, send home a note asking students to bring them in the day before or day of the experiment.
  6. Assign student partners. I use the Group Maker Tool from Super Teacher Tools to make my random groups.


The Day Before

  1. Pass out the sundial sheet and one silhouette to each student. Have your students bend the figures’ feet up at the ankles and glue the feet down to the paper so the figure faces north. The figure should stand up.
  2. Explain to students that they'll be going outside five times the following day to trace their shadows and record observations.
  3. Pass out the shadow observation form. Ask students to write down their prediction about what will happen the next day.

Experiment Day

  1. Students gather all materials they need (listed on their data collection chart) and head outside.
  2. Assign spots for your groups of two about 20–30 feet apart. Make sure all students locate north. I have students write N, S, E, W around them in chalk on the ground as a point of reference throughout the day.
  3. With your class, note the location of the sun. When we go out first thing in the morning and note the sun's position, we normally use the terminology, “the lower part of the eastern sky.”
  4. One partner marks an X on the ground in chalk as their starting point, and then labels the X with their name.
  5. That student then stands on the X, facing north while their partner traces their shadow. Both students should work together to measure the shadow from heel to the top of the head.
  6. Inside the shadow, record the measurement and the time the measurement was taken.
  7. Students switch roles and repeat the procedure.
  8. Before going in, students record all of the information on their data collection chart.

Back in the Classroom

  1. Have students write down all of their information and their observations in sentence form on the shadow observation sheet. I normally guide the students on this first one, modeling on the SMART Board. A first observation might sound like this: When I first went outside at 9:30 a.m., the sun was in the lower part of the eastern sky. I faced north and Sarah traced my shadow. It was long and skinny, much taller than I am. It measured 96 inches long, and it was pointing towards the northwest, but closer to the west than the north.
  2. Students make a written prediction of what they think will happen next time they go outside.
  3. Next, students take their sundial sheet with the silhouette and draw the precise location of the shadow along with its length. To help them do this, I darken the room and have students use their flashlights to replicate the sun’s position. This is a really important component because it allows the students to start realizing that as the light source moves, so does their shadow.

Summing Up

Go through these exact procedures four more times during the day. The student must always stand on their original X to begin. As the day progresses you will love how your students marvel at what is happening with their shadows. At the end, have your students write a summary of what they observed. Some of the things they will take away from the day:

  • Shadows are longest first thing in the morning and shorten until the sun is directly overhead (noon or 1 p.m. depending upon Daylight Saving Time.) Shadows begin to lengthen once again after midday.
  • The sun moves across the sky from the east to the west through the day.
  • A straight line can be drawn from sun’s location to the shadow’s direction.
  • Their shadows moves in a circular, clockwise direction. Thus, they are a type of sundial.

Questions for discussion:

  • Why do the shadows change throughout the day? (Because the sun’s location is changing throughout the day and the object blocking the light—them!—is not.)
  • What do you predict will happen if you keep going out until sundown? (The shadows will continue lengthening and moving in a clockwise direction.)
  • What do you predict would happen if you went outside at the same times tomorrow? In a different season? At night? 

Claim, Evidence, Reasoning

We began our day wondering how we could tell time without a watch. During our light unit, my class gathered information they could use to answer that question. Below is a chart we created during our study. I'll be doing a later post on using Claim, Evidence, Reasoning techniques, and this chart is just one of the components.

I know I'm providing a memorable educational experience for my students judging from the reactions it provoked in my previous classes. While we were busy tracing and measuring a few weeks ago, former students out for recess all gathered around to watch, talking about how they remembered doing the same thing when they were in my class.

Let me know how you get your class engaged in science and other parts of your curriculum. 

Books I Used With This Unit

Comments (7)

Thank you so much for this unit! I did this today with my 3rd graders, and they were literally buzzing about it all day. The conversations that we had, and the discoveries that they made, were way better than any other sundial/shadow/light project that I could have done with them. Thank you SO MUCH for sharing!!!

That's great to hear! I love how excited my kids get about their discoveries when they do this activity too! thanks for sharing! Genia

Thank you so much for this unit! I did this today with my 3rd graders, and they were literally buzzing about it all day. The conversations that we had, and the discoveries that they made, were way better than any other sundial/shadow/light project that I could have done with them. Thank you SO MUCH for sharing!!!

Amazing unit--sending it out to a bunch of my friends!

Thanks! Let me know how it goes. ~Genia

This is a popular outdoor project, in the UK.

You can actually get a uniquely 'personalised'
set of Project Plans (specific to your school),
which will allow you to mark an accurate Human
Sundial on your playground - the children's own
shadows tell correct clock time, and it even
changes itself for any 'Daylight-Saving' time.

See more information at www.sunclocks.com

Martina Addiscott.

Thanks so much for the info! I will definitely check it out for next year. I am always looking for ways to tweak and improve my lessons. ~Genia

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