The steamboat was invented by Robert Fulton at the beginning of the nineteenth century. Fulton's steamboat was fashioned using the steam engine, which had recently been invented by James Watt. Eli Whitney is the man who invented the cotton gin and in so doing revolutionized the economy of the Antebellum South. His invention encouraged the use of slave labor and had lasting ramifications for the social, economic, and political makeup of the United States. William Gladstone and Benjamin Disraeli were rival politicians in Britain during the Industrial Revolution who each served as Prime Minister.

The Industrial Revolution occurred from about 1770 to 1850 (depending on which historian you ask). The Industrial Revolution is so named for the changes to industry that occurred during that time, most notably the change from handmade production to machinery-based production. The Industrial Revolution began in England in the later decades of the eighteenth century and rapidly spread to Europe, the United States, and around the world. 

George Stephenson built the world’s first inter-city railway line. The steam locomotive line was built between two major cities of industrial power in early Victorian-era England, Manchester and Liverpool. Robert Fulton is the person credited with inventing the steamboat; James Watt is credited with the invention of the steam engine, and Robert Peel and William Pitt were Prime Ministers of England.

The Clovis culture was a group of Native Americans who most likely lived 8,000 to 10,000 years ago. The culture is known for their distinctive stone arrow points, which feature a flaked construction to form a sharp point. The Clovis culture gets its name from the city in New Mexico nearest to the location where the first representative spear points were found in 1926.

The Egyptian pyramids were built many centuries before the Mayan pyramids, but the Mayans developed pyramids independently. For both people, their pyramids had great religious and cultural significance, and both served specific functions. The Egyptian pyramids served as Pharoahs' tombs and were smooth faced. The stepped Mayan pyramids served ceremonial and governmental functions that required priests and kings to climb them.

Both of these inventions come from China. They are significant because the magnetic compass facilitated marine exploration and trade while gunpowder led to advancements in weapons technology.

Throughout most of recorded human history, the population of the world could be counted in the tens or hundreds of millions. At the beginning of the twentieth century, the Industrial Revolution and increased agricultural output had pushed the total population to around 1.5 billion. The population now is around 7 billion. This means that the planet grew by roughly four and a half billion people in the hundred years that make up the twentieth century. The primary impetus for this massive growth was the Green Revolution, which occurred in the 1950s and 1960s. Increased use of pesticides, herbicides, fertilizers, and so on greatly impacted the global food supply. The impact was felt most notably in developing nations. In addition to providing the means for massive population growth, the Green Revolution is also credited with saving perhaps as many as one to two billion people from starvation.

The Panama Canal was primarily built between 1904 and 1914 by American authorities. The Canal cuts through the territory of Panama and greatly reduces the amount of time required to ship goods from Europe, Asia, and Africa to the Western coast of the United States and South America. The Panama Canal remained under American ownership until 1999, when it was passed over to Panamanian control.

After the Napoleonic Wars at the start of the nineteenth century, many states were redrawn and reorganized. Additionally, the romantic and revolutionary movements of Europe in the early nineteenth century highlighted the shared histories of certain peoples. The desire for shared cultural, language, and religious heritages to be united in one state would both create modern Italy and Germany, while also spelling the destruction of multi-ethnic and multi-lingual nations like the Austro-Hungarian Empire by the end of World War I in 1918.

The Iron Law of Wages is a long-held economic theory that states that in the long run, real wages always tend towards the bare minimum necessary to keep workers working and alive. There remains some historical debate over who should be given credit for the Iron Law; for the purposes of this test, it is necessary only to know that it was proposed first by David Ricardo, who himself was working on similar, earlier theories espoused by Thomas Malthus. And, indeed, many historians claim Malthus as the original proponent of the Iron Law of Wages. As this is a somewhat controversial question, the test makers will err on the side of caution when presenting it. This means that if you see a multiple-choice question about the Iron Law of Wages, you will not see both Malthus’ and Ricardo’s names, as they could each reasonably be considered the correct answer. Malthus is, however, most commonly remembered for his theory about the unsustainable rate of population growth and his predictions about the disastrous consequences this would have for social and economic progression. Long story short: on many standardized tests, David Ricardo is associated with the “Iron Law of Wages," Thomas Malthus with An Essay on the Principle of Population, which contains many ideas similar to Ricardo’s.