Educator How-to: Tectonic Chocolate Bars

The earth is vast and its surface seems huge. However, the earth’s crust only makes up 1% of the earth’s mass — subsequent layers (the mantle and the core) make up the other 99%.

So, why do we care about the earth’s crust (besides the fact that we live there)? It consists of tectonic plates that move around, and where they hit, we get nature’s most impressive formations — Earthquakes and Volcanoes. Because the crust is so vast, it is hard to see the minor changes that occur daily. We tend to notice the big changes like mountains and effects from earthquakes.

In Houston, we don’t get to see either of those things! Luckily, the Houston Museum of Natural Science has Nature Unleashed: Inside Natural Disasters on exhibit right now. In Nature Unleashed you can see how the earth’s tectonic plates shift and learn about the earthquakes that can result, build your own volcano and watch as it explodes molten rock along the mountain side. You can even experience the inside of a tornado, and see some of the aftermath found in several cities.

Nature Unleashed: Inside natural DisastersIf you can’t make it to the museum, you can always show the effects of tension, compression and shifting on the earth’s crust using a simple chocolate bar!

Materials

  • Snack-sized chocolate bars (Milky Way and Snickers work best because of the caramel)
  • Wax paper or plates to place candy on while working

Procedure

  1. Tell the students that the earth’s surface is constantly changing. The crust is formed by tectonic plates which float on the plastic layer of the mantle called the asthenosphere. Where these plates interact, we notice changes on the earth’s crust. The chocolate on this candy bar is going to mimic some of those changes. This time I used Milky Way.

Structure of the Earth

  1. Have the students use their fingernail to make some cracks in the “crust” near the center of the candy bar. Ask them what they notice about the cracks in the crust?

Science Education

  1. Next, demonstrate tension by pulling the candy bar apart slowly. Notice how the crust shifts on top of the caramel layer. The caramel is the exposed upper mantle also known as the asthenosphere. It is this layer that allows the tectonic plates to move around. Sometimes this tension between plates can form basins or underwater ocean trenches.

Science Education

  1. The students should then place their chocolate bar back together gently. To demonstrate another way the earth’s crust moves, ask the students to move one half of the candy bar forward and pull the other half backwards. This is an example of a strike-slip fault. Notice how the chocolate changes at the fault line. This mimics the bending, twisting and pulling of the rocks that can occur at a fault.

Science Education

  1. Lastly, ask the students to push the two ends of the candy bar together. Notice how some of the chocolate pushes up and some even slides on top of another piece, showing how mountains can be created on the earth’s crust.

Science Education

  1. Now that you’ve seen what the earth’s crust can do, feel free to allow your students to eat their new landform creations! 

And don’t forget to come check out Nature Unleashed: Inside Natural Disasters showing now through September 14!

The sweetest story: Learn about the chocolate revolution at an HMNS Distinguished Lecture

On cold nights, one of the best comforts out there is hot chocolate. You come home from a long day’s work, take off your coat, defrost a bit (OK, we’re in Houston, so just go with me here), boil up some water, add in the mix and mmmm … hot chocolate.

Oh, the convenience of it all! But have you ever wondered what the real story of this drink was?

hot-chocolate

As modern Americans, we might consider hot chocolate to be a unique invention, seeing that much more of the chocolate around us exists in its hard candy form. But really, this drink harkens back all the way to early Mesoamerican cultures.

Cacao cultivation started as early as 1400 B.C. by the Olmec civilization. From residue left on pottery, we can tell that the Olmecs used the bean to create a fermented drink, most likely used in religious ceremonies. The Maya borrowed the Olmec’s cultivation techniques but created a drink far more recognizable to today’s chocolate connoisseurs, creating the first “modern” chocolate 2,000 years ago. The drink was associated with fertility and was also used in a ritual setting.
The Aztecs, in turn, borrowed from the Maya and seasoned it with vanilla, chili pepper and achiote to create a bitter, frothy drink called xocolatl. By this time, the beverage had become a luxury item for wealthy Mayans. Europeans would pick up on this when they came to the New World, and maintained chocolate as a luxury item for European courts until the Industrial Revolution would make chocolate accessible to the masses.

In 1828, the cocoa press was invented by Dutch chocolatier Coenraad J. van Houten. The press created a fine powder from roasted cacao beans, which dramatically lowered the production price. This, in turn, paved the way for British chocolatier J.S. Fry to make the world’s first chocolate bar in 1830. In 1875, the Swiss were the first to add powdered milk to the mix, creating milk chocolate.

Today chocolate is a worldwide industry, with 45 percent of chocolate revenue coming from Europe and two-thirds of cocoa produced in Western Africa. So to all the chocoholics out there, be grateful for the rich history of chocolate, which has made it so readily available to us today!

Can’t get enough chocolate history? Come to HMNS on Tues., Feb. 4 for “Chocolate, A Revolution in a Cup” as part of our Distinguished Lecture series. The lecture starts at 6:30 p.m., but come early for a chocolate frothing demonstration … and stick around after to taste unique chocolates from Araya Artisan Chocolate!

HMNS Distinguished Lecture
“Chocolate, A Revolution in a Cup”
Rosemary Joyce, Ph.D.
Tues., Feb. 04, 2014
6:30 p.m.

This lecture is cosponsored by Archaeology Institute of America Houston Society. Get tickets!

Teachers, get credit for hearing the chocolate doctor at a special Teacher Tuesday just for you:

ExxonMobil Teacher Tuesday
“Domestication of Plants: Chocolate”
Tues., Feb, 4, 5
8 p.m.

Examine the natural science and yummy cultural history of chocolate with hands-on classroom activities. Then attend lecture by Dr. Rosemary Joyce, who will tell how the cacao plant was domesticated to produce chocolate. Purchase tickets.

Chocolate

This weekend kids will be running around the lawns hunting Easter eggs. Others will be eagerly chomping down on chocolate Easter bunnies. None of them will even wonder where all of that good stuff came from.

It has been a while already, but the museum hosted a wonderful exhibit on chocolate. It told the story of the origin of the cacao tree (northern South America), and how it made its way into Mesoamerica, into the Maya and Aztec cultures. We also learned how the Spaniards brought the substance to Europe, and added sugar, rather than the chile peppers once used in Mexico. More people were able to drink it we were told, as consuming chocolate was the prerogative of the elite in the New World. 

Or so we thought. As someone once said, that’s not entirely accurate. Enter Pueblo Bonito, New Mexico.

 
Aerial view of Pueblo Bonito, December, 2009. Image Wikipedia  (Bob Adams photographer)

Excavations conducted in 2009 at Pueblo Bonito, New Mexico, showed that chocolate beverages were consumed at the site. At that time, 2009, this constituted “the first proof of chocolate use in North America north of the Mexican border.” In a recently released update on the project we read that out of 75 drinking vessels found at the site, no less than 50 still had minute traces of theobromine in them. What makes all this even more interesting, aside from claims of “first proof of chocolate use”, is that this consumption was not limited to the upper crust of society.

Here is another question that comes up right away. How did the chocolate get up there? New Mexico is too cold for cacao trees to grow, unless, of course, you use a greenhouse. It turns out that Pueblo Bonito was part of a trade network extending from the Southwest all the way south into what we call Mesoamerica. Another wonderful exhibit, called the Road to Aztlan explored commercial exchanges between these two culture areas. Parrots were sent north, turquoise was sent south. Now it seems that in addition to the parrots (much prized because of their feathers, it is thought), chocolate was also shipped north.

All of this dates back to about the 11th through 14th centuries AD, a time when some of the Classic period Maya had experienced their infamous “Collapse.” Sites like Chichen Itza and Mayapan traded places as the centers of power in Yucatan. The site of Tula, rather than Teotihuacan (already in ruins) and Tenochtitlan (a bit too early still for them to manifest themselves as a powerhouse) ruled the roost in Central Mexico. Maya chocolate aficionados were imbibing as early as the 11th century BC, maybe even earlier.

The glyph for “kakaw”  appears on many Maya pots and inscriptions. One of the pots is a chocolate drinking vessel found at Rio Azul, Guatemala. What makes this vessel so incredible is that it has a screw top. Notice in the images below: the neck of the vessel has a groove, the lid has two protrusions allowing one to place the lid onto the pot and then twist it to close it.

 
Rio Azul cacao vessel on display at the Museo Nacional de Arqueología y Etnología,
Guatemala City. (Photograph by Dirk Van Tuerenhout).
 
Lid for the Rio Azul cacao vessel on display at the
Museo Nacional de Arqueología y Etnología, Guatemala City.
(Photograph by Dirk Van Tuerenhout).

For the Love of Chocolate

Truffles
Creative Commons License photo credit: Frank_BB

In light of the upcoming Valentine’s Day festivities, I thought we should all take a moment to learn something new about a traditional Valentine’s Day gift. I’m talking about chocolate, of course! Did you know…

Chocolate syrup was used as the blood in the famous shower scene of Alfred Hitchcock’s movie, “Psycho.”

A quote for you (I think this soldier liked chocolate a little bit): “Chocolate is a divine, celestial drink, the sweat of the stars, the vital seed, divine nectar, the drink of the gods, panacea and universal medicine.” – Geronimo Piperni, quoted by Antonio Lavedán, a surgeon in the Spanish army, 1796.

A chocolate history legend states that the Aztec god Quetzalcoatl brought cacao to earth and was thrown out of paradise for giving it to man; it was believed that only the gods were fit to drink chocolate!

In the 1500s, when chocolate first made its way in to Spain, it was considered a health food and a medicine! Many doctors of the time prescribed it for curing fevers, cooling the body, aiding in digestion, and alleviating pain.

DANGER! Chocolate is poisonous to dogs (and other domestic animals); the Theobromine found in chocolate is a stimulant, especially affecting the heart muscles, and can be too much for small animals. So be careful if you have pets.

The melting point of chocolate is just below normal body temperature, so it literally melts in your mouth! Mmmmm…tasty.

Smarties: Inverted Double Spiral (-1,2)
Creative Commons License photo credit: gadl

In 1940, M&M’s were invented by the MARS Company for soldiers going to WWII.

The biggest bar of chocolate ever made was made in Italy in 2000 and weighed over 5,000 pounds. The largest slab of fudge weighed over 2,000 pounds and was made in Canada.

Currently, 40% of the world’s almonds and 20% of the world’s peanuts are used by chocolate manufacturers. One pod from a cacao tree (the plant from which chocolate is derived) contains about 30-50 almond-sized seeds. This is enough to make about 7 milk chocolate bars.

And, finally, 63% of Americans buy chocolate for themselves when buying it for someone else. So go splurge on your sweetie! But don’t forget to grab a treat for yourself, while you’re at it.

This Valentine’s Day, be sure to pick up some chocolate for your special someone, and don’t worry if you don’t have any extraordinary plans. Come on down to Love Bugs, the Museum’s Valentine’s Day bash!

And if, perchance, you are spending this February 14th alone, you should still go out and grab your favorite chocolaty treat; studies show that chocolate has anti-depressant qualities and mood-boosting goodness.