One of the greatest mysteries of ancient times is how the Egyptians managed to raise huge obelisks using very simple technology. Obelisks were tall monuments dedicated to the pharaoh and the sun god. Each obelisk was quarried from a single piece of granite weighing up to 500 tons and reaching as high as 100 feet. Even an entire army of Egyptians lacked the physical strength to lift or pull these enormous stones upright. There are no written records to reveal how the Egyptians raised their obelisks. This remarkable task puzzled engineers for thousands of years. After failing to raise an obelisk with simple machines, such as levers and pulleys, a team of modern engineers solved the mystery using a sandpit and the force of gravity. (Students can view a series of pictures and passages describing how the task was accomplished by going to: www.pbs.org/wgbh/nova/egypt/raising.) Based on this recent engineering effort to raise an obelisk, this article explains how students can simulate the task by constructing and testing a small engineering model. Upper elementary and middle school students will find designing the model and raising the obelisk a challenging, rewarding, and exciting project.
The technological task of raising an obelisk contributed to the religious and political stature of the Egyptian empire. Obelisks stood at temple entrances and were inscribed with pictographs (hieroglyphs). Each obelisk contained many pictographs dedicated to the pharaoh, including vertical rectangles with curved corners called "cartouches" Each cartouche was dedicated to a royal family. For example, in the photograph, the upper cartouche is a phonetic spelling for the Pharaoh Ptolemy, and the lower cartouche spells his wife's name, Cleopatra. Egyptian hieroglyphs remained a secret language for centuries until the French linguist, Champollion, deciphered Ptolemy's name inside a cartouche.
Engineering Design Process and ITEA Standards
The task of constructing and testing a classroom model follows the basic engineering design process: identifying the problem, developing a solution, constructing a prototype, and testing the solution. Having students apply this process addresses several technological literacy standards (ITEA, 2000/2002/2007). For example:
* Standard 7 refers to the "influence of technology on history."
* Standard 8 calls for an understanding of the "attributes of design"
* Standard 9 refers to the need for students to be involved in "engineering design."
* Standard 11 calls for students to "apply the design process."
The design and testing of models also addresses the technology and engineering standards required by most states. These standards call for a constructivist approach, including the testing of prototypes in the classroom.
Key Concepts for the Engineering Model
The students should be introduced to the following key concepts before they begin designing the model for raising an obelisk. The concepts will help the students focus on the importance and interdependence of the materials and forces at work.
* Obelisk--a tall, tapered, four-sided monument with a pyramid at the top.
* Rigging--ropes to pull the obelisk up the incline and brake its descent onto the pedestal.
* Sandpit--an enclosure that contains sand, a pedestal, and inclined plane.
* Release holes--holes on opposite sides of the sandpit for releasing sand.
* Pedestal--a base with a turning groove for raising and supporting the obelisk.
* Turning groove--a v-shape carved on the top of the pedestal to help position the obelisk.
* Inclined plane--a slanted surface for moving the obelisk upward or downward.
* Mechanical advantage--a machine that makes it possible to use less effort.
* Pivot point--upper edge of the sandpit wall for rotating the obelisk downward. …