Students will create a convection box.

Photocopies of Incense Burner Lid
Convection box (or shoebox, 2 toilet paper rolls, plastic wrap, tape)
Candle
Incense cone or other source of smoke
Ice
Petri dish bottom
Small candle
Matches

1.  Explore the Art.

Incense burners are comprised of two parts: a bottom hour glass shape base which holds the incense and a top lid.  Although this specfic example is missing the bottom, the top provides a sense of the importance such an incense burner played in ritual ceremonies. 

With your students, view the Explore the Art in the Learn About the Art section.  Imagine the incense burner in use with smoke billowing from the openings in the eyes on the face and sides of the lid.

• What words would you use to describe the effect of the incensario in use?
• Why are the details so important?
• What emotions do you think the artist wants the viewer to feel when looking at this piece?
• What scientific knowledge do you think the maker of this lid must have possessed to ensure that it created such an effect?

2.  How is an incense burner like a convection box?

This incense burner functions much like a convection box.  Convection is the process in which warm air rises and cool air sinks resulting in vertical transport and mixing of atmospheric properties.   

With students, define the terms temperature and density and discuss the mass and volume of air.  See the Handouts section for additional background information.

• Look at the incense burner again.  Why does the smoke from the incense burner lid move upward?
• Consider other examples of convection.  For example, why does a hot air balloon rise?

3.  Experiment with a convection box.

Have students conduct the following experiment in groups of two to four.  Use the illustrated activity sheet in the Handouts section for visual references.

Note:  If a convection box is not available, cut out the long side of a shoebox and cover the cut side with plastic wrap.  Cut two holes in the top just wide enough to accommodate two toilet paper rolls.  Because these activities use candles and lit incense, teachers may want to demonstrate this convection box to the students.

a)  Study the convection box and make a rough sketch of it.  If hot water or a candle was placed on the left side of the box and the incense in the center, predict from which of the two chimnies the smoke will rise.  Draw a picture to illustrate the rising smoke. 

b)  Draw another picture of the convection box, but now imagine that the heat source has been replaced by ice water.  Indicate on your drawing the direction you predict the smoke will move.

c)  Place a short candle or a Petri dish bottom holding hot water on the left side, directly under the glass chimney and place the incense cone or smoke source in the center.  Light the incense and observe.  Draw a picture of what you see.

d)  Apply scientific terms to the drawings.  The terms high and low describe the air pressure.  The terms moist and dry describe the amount of water vapor present and the terms wamr and cool describe the air temperature.  Label your diagrams with the words High, Low, Moist, Dry, Warm, Cool to indicate where pressure, humidity, and temperature may differ in the box.

e)  Place ice in the Petri dish and set it on the left side under the chimney.  Draw your observations and label the diagram with the terms high, low, moist, dry, warm, and cool.

f)  Predict what will happen if you set up the convection box so that the hot water or candle is on one side of the box, the ice on the other, and the incense in the center.  Observe, draw, and label.

4.  Compare the convection box to the incense burner.

The incense burner contains openings to release the smoke.  Have students use their observations from the convection box to answer the following questions:

• What would happen if you were to heat air or water in the incense burner?
• What would happen if you were to heat air or water and the incense burner contained no openings to release the smoke?
• How do you think the maker of this incense burner knew how many openings were required so it would function properly?

Look closely at the incense burner lid.

• Does all of the smoke escapes at the same level?  If not, explain the different characteristics of the air (pressure, humidity, and temperature) at the various escape points.
• Considering what you know about how this object works, what do you think the maker of this incense burner lid would need to know about science in order to make it function?

Conclusion

Revisit the Explore the Art in the Learn About the Art section. What additional scientific knowledge must the maker of this incense burner possess? Consider the materials used to make the incensario, the decorative elements on the incense burner lid and the artist´s familiarity with the natural world.

Extensions to the lesson

Language Arts: Creating Nahuatl Traditions
Teotihuacán, where this work of art is believed to originated from, is a Nahuatl name meaning "city of the gods."  According to the local beliefs, this was where the gods gathered to plan the creation of man.  As a homework assignment, have students research Nahuatl stories and poetry.  What are the common themes?  Using the Incense Burner Lid, write a poem or story that tells a story about it.

Math: Pyramids
Did you know the Pyramid of the Sun, located in the ancient city of Teotihuacan, is the 3rd largest pyramid in the world?  Find the dimensions of this pyramid and the other two larger pyramids in the world.  How much larger is each pyramid from the other?  Can you find the fourth largest pyramid in the world?

Social Studies: Teotihuacan
Today the ancient city of Teotihuacan is one of Mexico´s most visited archaeological sites.  Research the city Teotihuacan and its peoples.  Focus on the architecture and layout of the city.  What do you think daily life was like?

Art: Working with Clay
Discuss the techniques and tools artists use when working in clay and have groups of students experiment with these different methods and tools.  Compare final products and discuss the versatility of this medium.

 

Incense was used in religious ceremonies throughout Mesoamerica and this incense burner lid was created and designed to honor an ancestor of an important family. Use this lesson to examine the scientific knowledge of the peoples of Teotihuacán and to examine the function of this object using a scientific framework.

•  Why do you think incense burners in such good condition are a rare find?
• Traces of the original paint remain on this remarkably preserved work. The bright red coloring comes from cinnabar (dried mercury), which is extremely poisonous when touched or inhaled. How do you think the incensario looked when it was first created? How would the vibrant colors enhance its effect?

• What words would you use to describe this incensario? How would you explain it to someone who has never seen it?
• Discuss symbols. Look at the adornos on this lid. What might these symbols have meant to Pre-Columbian people? What symbols are important to us today?
• Today, the deserted streets, pyramids, and temples of Teotihuacán are popular with tourists. People travel from all over the world to see the remains of this great culture. Research Teotihuacán as a travel destination. Why do you think people want to visit? What can they learn from the city?
• Trade with the Mayans was important to Teotihuacános. Why? What goods might they have imported and exported?
• The meaning of the feathered serpent deity at the top of this lid is uncertain. Similar imagery appears repeatedly throughout ancient American cultures and is usually associated with the sky, rain, and fertility. What do you think it might mean here? Have you seen a symbol like this before?

The central Mexican city of Teotihuacán was once the cultural, religious, and economic center of the Western world. Teotihuacános used incensarios, or incense burners, as a part of their religious ceremonies. These lavishly decorated objects included a lid, like the one seen here, and an hour-glass shaped base, which is now missing.

Copal, a resin derived from tropical trees, was burned in the base and smoke poured from the openings on the lid. This was meant to mimic cremation, sending clouds into the heavens to mix with the life-giving rains.

Imagine smoke rising out of the face´s eyes and the serpent´s mouth. Describe the mood you think this would create.

Although the maker of this incense burner (incensario) lid is unknown, there was probably more than one artisan involved in the construction of this common ritual object. Individual pieces, such as the base, lid, chimney, and armature, were mass-produced in ceramic workshops located throughout the city of Teotihuacan, usually near temples or other buildings that appear to have had a religious affiliation. Clay symbols called adornos that decorated incensarios were similarly usually mass-produced with molds in workshops. However, many of the adornos on this lid were handmade, which makes it unusual. Adornos could be individually selected and placed on an incensario to serve the worship practices or other representational needs of the person commissioning the piece. Such commissions were probably common because no identical Teotihuacán incensarios are known to exist.

 

Incensarios were used in many kinds of religious rituals throughout Mesoamerica. Like this one, they were covered with layers of complicated symbolism. The face in the middle of this lid may represent a deceased ancestor or deity within a temple. The butterfly, flower, and seashell adornos—symbols of transformation, the soul, war, water, and fertility—would have been appropriate emblems for a vessel honoring ancestors or the gods. The triangle and rectangle motif that appears three times between the flowers in the headdress is the glyph for a year and is also related to warfare. The head of the feathered serpent at the top of the lid represents an important deity to which the largest temple at Teotihuacan is dedicated.  A popular god in many Mesoamerican cultures, it was called Quetzalcoatl by the later Aztecs and was usually associated with the sky, rain, and fertility.

 

At Teotihuacan, an incense burner consisted of an elaborate conical lid and an hourglass base (now missing from this work). The copal, or tree resin, burned in the base sent smoke wafting heavenward through the lid as part of a ritual and prayer. This smoke represented rain clouds and, ultimately, fertility. In this example, the smoke would have been expelled from the serpent’s mouth at the top of the lid and from the eyes of the face in the center. Most of the adornos on this lid were handmade and attached using lime-stucco cement. Traces of the original paint remain on this remarkably preserved work.

 

The ruins of Teotihuacan lie approximately forty-five miles northeast of modern-day Mexico City. In its day, the city was a cultural, religious, and economic focal point of the Mesoamerican world (from about 450–650 A.D.). With a population of 120,000 to 200,000, the area was one of the largest preindustrial cities in the world at the time, and people converged at its center to exchange goods and to pay homage to their gods. Centuries later, the Aztecs (c. 1325–1521) stood in awe of the architectural sophistication of the ruins of the city’s temples and pyramids. In honor of that splendor, they named it Teotihuacan, a word in their native Nahuatl language meaning “city of the gods,” and consecrated the ruins as a sacred and ceremonial site for worship.