Rubies are precious gemstones that range in color from light pink to blood red and are second only to the diamond in hardness. They are found chiefly in Myanmar, Thailand, and Sri Lanka and are classified among the most valuable of gems. The rare star ruby, which shows an internal star-shaped formation when cut into a cabochon, is an example of a gemstone whose value is actually increased by an inclusion. Why can rubies be found beneath building foundations in some Asian countries? Discuss
Source: The Free Dictionary
The fortress of Terezín was constructed in the late 18th century in what is now the Czech Republic. In the early 1900s, it held famed prisoner Gavrilo Princip, who assassinated the Archduke of Austria, causing the outbreak of WWI. The Nazis took control of Terezín in 1940 and quickly turned it into concentration camp called Theresienstadt. The camp was presented to the outside world as a model Jewish settlement, but of the approximately 144,000 Jews sent to Theresienstadt, how many survived? 
Red Square, located in Moscow, is one of the most famous city squares in Russia, with a rich history that is reflected in many works of art. After the square was cleared of buildings in 1493, it became Moscow’s primary marketplace as well as the site for various ceremonies, proclamations, and coronations. During the Soviet era, Red Square maintained its significance and was the site of the 1945 victory parade held after the defeat of Nazi Germany. What is the origin of the name “Red Square”? 
The Alhambra is a palace and fortress complex built during the Middle Ages by the Moorish monarchs of Granada. It is the finest example of the once flourishing Moorish civilization’s architecture. Its halls and chambers surround a series of open courts, and the interior is adorned with magnificent examples of honeycomb and stalactite vaulting. Detailed geometric designs in marble, alabaster, and carved plaster also decorate the interior. What artist came to study the Alhambra’s tiles in 1922? 
Stainless steel, which was developed in England in 1913, has a high tensile strength and resists abrasion, corrosion, and rust because of its high chromium content. Over 150 grades of this iron-carbon alloy now exist, and it is widely used to make cookware, cutlery, hardware, surgical instruments, watches, appliances, building materials, and industrial equipment. It is also used as a structural alloy in automotive and aerospace assembly. What is the passivation layer? 
Moholy-Nagy was a Hungarian painter, photographer, and designer. His experiments with photograms and kinetic “light space modulators” reflect the way in which his art was influenced by constructivism, an abstractionist movement characterized by the use of industrial materials to create nonrepresentational, often geometric objects. One of his greatest contributions to modern art was his teaching, which deeply influenced American commercial and industrial design. Where did he teach in the 1920s? 
Invented in 1974 by Hungarian sculptor and professor Erno Rubik, the Rubik’s Cube is now said to be the world’s best-selling toy. More than 300 million of these colorful, square puzzles have been sold worldwide. The standard Rubik’s Cube has 54 square faces—nine on each side—covered by stickers in six solid colors. When the puzzle is solved, each side of the cube is a single solid color. What is the current world record for solving a Rubik’s Cube? 
Scientists believe that mastodons, elephant-like mammals that flourished worldwide from Miocene through Pleistocene times, first appeared nearly 4 million years ago. Though the large, furry, prehistoric mammals resembled wooly mammoths, the two had distinctly different dental and skeletal structures. Hunting may have played a role in the extinction of the mastodon 10,000 years ago. In what US states have mastodon remains been found? 
Snowball Earth is a strongly disputed hypothesis developed to explain sedimentary glacial deposits at tropical latitudes from the Cryogenian period. The hypothesis proposes that, about 800 million years ago, the Earth was entirely covered with ice and that multicellular evolution accelerated when the climate began to warm up. Some dispute the feasibility of an entirely frozen ocean and prefer a “slushball” scenario to explain the ice’s rapid movement. How could life survive in such a climate? 
In 1896, a banquet was planned in Moscow’s Khodynka Field to celebrate the crowning of Nicholas II as Tsar of Russia. When rumors spread of lavish gifts to be bestowed by the new leader, hoards of people began gathering at the coronation square. Suddenly, rumors of a gift shortage began circulating through the crowd. In the resulting disorder and panic, 1,389 people were trampled to death and another 1,300 were injured. What were the coronation gifts that inadvertently led to this disaster?