Aztec Sundials

Did you know that the Aztec calendar stone had eight holes across its face that were used by the Aztecs to turn it into a sundial?

This online activity page guides teachers and students through the process of creating and using a sundial to find the directions N, S, E, and W, and to tell time.

Click on the video clips below to see learning and doing in action! (Note: these are large files and may take some time to download.)

Photo 1: Making a sundial

Photo 2: Sundials at Noon

Clip 1: Teacher and student discuss sundials

Clip 2: Sundials in action

Using the photos and video clips above, parents and teachers can use the lesson outline below to bring Aztec sundials to life!

[Note: the photos and clips are taken from a related project conducted at a different local elementary school.]

Lesson Introduction and Goals
This lesson will introduce students to some of the scientific findings and mythic beliefs of the Aztec civilization of early Mexico. During the lesson, each student will create a sundial for future experimentation. At the conclusion of this lesson, the students will be able to:

  • Describe some of scientific knowledge of the Aztec culture.
  • Convey some of the Aztecs' mythic beliefs about the sun.
  • Understand why modern science has arrived at new conclusions about the sun.
  • Return to their classrooms to conduct a simple sundial experiment.

Time Allotment
45 minutes

Materials

  • One 8.5x11 poster board for each team of two (2) students
  • One pencil for each student team
  • One quarter-size piece of putty or clay for each student team
  • One Aztec Sun Stone Calendar sheet for each student (any photo of the calendar stone will do)

Advanced Preparation

  • Gather materials

Procedure
A. Tap Prior Knowledge/Pre-evaluation (10 min.)
Ask your student(s) to tell you what they know about the Aztecs. Write their answers on a chalk board or on paper. Then ask them the following questions and write these on the board/paper:

  • How do we know science about the sun today?
  • How do we know what the Aztecs thought about the sun?

Explain to the students that we know about the sun today by studying it with telescopes and satellites. We observe it closely and keep data about it. Then we think about the data to make conclusions.

B. Share With Neighbor (Interpretation) (25 min.)
Then pass out the sun calendar stone handouts (or a photo of the calendar stone). Give your students time to discuss (in pairs if appropriate) what they think about the sun stone. Can they tell what the Aztecs thought about the sun from this artifact? Ask for ideas and put them on the board. Some of the ideas might include: mean face, claws, animals, pictures, decoration.

Explain to the students that the science called archeology is what we do when we study things left behind by earlier peoples. Help the students interpret the sun stone calendar (bolded text is most important):

  • The Aztecs (who called themselves "Tenochca," craftsmen) lived in central Mexico ("Tenochtitlan," now Mexico City) from between 1300-1375 until around 1521.
  • They were a highly advanced society with farming, medicine, religion, ritual, science, and writing (pictographs).
  • Tenochtitlan, built around 1440, included roads, temples, and aqueducts to provide water.
  • They prospered under several leaders, including Chief Moctezuma, until 1519-1522 when the Spaniards invaded.
  • The Aztec sun calendar is a circular stone with pictures representing how the Aztecs measured days, months, and cosmic cycles. The calendar is evidence of the Aztec's knowledge of astronomy and mathematics.
  • The calendar contained the pictographs for their days, months and suns (cosmic cycles).
  • The stone is 3.6 meters (12 feet) in diameter and weighs about 24 metric tons. It took 52 years to complete, from 1427-1479, it is believed due to the use of only stone tools.
  • This calendar is 103 years older than the Gregorian calendar, which is used worldwide today.
  • Originally the calendar stone was placed atop the main temple in Tenochtitlan, the capital of the Aztec empire. Today, Mexico City's cathedral stands on the site.
  • The Aztec calendar faced south in a vertical position and was painted a vibrant red, blue, yellow and white.
  • The stone was buried by the Spaniards when they conquered Tenochtitlan. The stone was lost for over 250 years until December of 1790, when it was found by accident during repair work on the cathedral. Today it is located in the National Museum of Anthropology in Mexico City.
  • Tonatiuh, the face in the center of the stone, is the fifth sun, his name meaning, "He who goes forth shining."
  • The four "movements" around him-the ways the four previous suns had come to an end (wild animals, wind, fire, and floods).
  • Human sacrifices were often made to Tonatiuh him to keep him strong. In the claws to the sides of the face are human hearts from sacrifices. Continuing outward, the next concentric circle shows twenty squares, each naming one of the twenty different days of the Aztec month. Clockwise these days are as follows: Twenty Days of the Aztec Month: Snake - Coatl Lizard - Cuetzpallin House - Calli Wind - Ehecatl Crocodile - Cipactli Flower - Xochitl Rain - Quiahuitl Flint - Tecpatl Movement - Ollin Vulture - Cozcacuauhtli Eagle - Cuauhtle Jaguar - Ocelotl Cane - Acatl Herb - Malinalli Monkey - Ozomatli Hairless Dog - Itzquintli Water - Atl Rabbit - Tochtli Deer - Mazatl Skull - Miquiztli
  • This arrangement and other markings on the calendar totaled 360 days (18x20), to which five dots were added inside the circle. These dots, known as Nemontemi, were sacrificial days.
  • Eight equally spaced holes appear on the very edge of the calendar. The Aztec placed horizontal sticks here and the shadows of the stick would fall on the figures of the calendar; thus the stone also served as a sundial.

C. Hands-On Activities and Explanations (5 min.)
What is a sundial? Start by showing pictures of sundials made in other times by other cultures.

Pass out to each student team of two a poster board, pencil, and clay.

1. Ask the students to draw a line lengthwise down the very middle of the paper.

2. Ask the students to place the ball of clay in the middle of this line.

3. Ask the students to place the pencil, eraser side toward the sky, into the center of the clay so that it sticks straight up. Then, using a lamp, demonstrate how the students will use the sundial to tell time.

  • Sundials were made more than 3000 years ago to tell the time of day.
  • The pencil in our sundials in called the gnomon (NO-mon) of the sundial; this means "the one who knows" in Greek.
  • At "local noon," when the sun is at its local zenith (but not necessarily directly "over head"), the shadow will fall directly down the due North line. So, if you know the rough time of noon, you can find North.

D. Introduce Scientific Principles and Relate Activities and Concept (5 min.)
Summary

  • We know about the sun today by doing science: tracking data with telescopes and satellites and making conclusions based on this data.
  • The Aztecs also did science. They had farming, medicine, math, and astronomy. Their science led them to have certain beliefs and myths, such as the five suns story.
  • The sun stone calendar is a record of the science and math the Aztecs did about the sun.
  • Archeology is the science of studying fossils and artifacts from older times to learn about the people who made them or about the animals that lived then.

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