English is the most spoken language in the world by total number of speakers (including second-language speakers), with about 1.5 billion speakers. Mandarin Chinese is the most spoken native language (about 940 million native speakers). English is the dominant language of international business, science, technology, and aviation. What is the most spoken native language in the world?

Portuguese is the official language of Brazil. Brazil is the largest country in South America and the only Portuguese-speaking country in the Americas. Portuguese is also the official language of Portugal, Angola, Mozambique, Cape Verde, Guinea-Bissau, São Tomé and Príncipe, and East Timor. What language do Brazilians speak?

English is a Germanic language, belonging to the Indo-European language family. It is closely related to German, Dutch, and the Scandinavian languages. English has been heavily influenced by French (after the Norman Conquest of 1066) and Latin (through religion and science). Which language family does English belong to?

Spanish is the most widely spoken language in South America (spoken in 9 of the 13 countries). Portuguese is spoken in Brazil (the largest country). The only South American countries that do not speak Spanish are Brazil (Portuguese), Guyana (English), Suriname (Dutch), and French Guiana (French). What is the most widely spoken language in South America?

Standard Chinese (Putonghua, also known as Mandarin) is the official language of China. It is based on the Beijing dialect. Written Chinese uses characters (Hanzi) rather than an alphabet. China also has many other dialects (Cantonese, Hokkien, Shanghainese, etc.), but Mandarin is the official language and is taught in all schools. What is the official language of China?

India has two official languages at the national level: Hindi and English. There are 22 scheduled languages recognized by the Indian constitution. Hindi is the most widely spoken language in India (about 44% of the population). English is used for government, business, and education. How many official languages does India have at the national level?

Arabic is the most widely spoken language in Africa (by number of speakers), followed by English, French, Swahili, Hausa, and Yoruba. Arabic is spoken in North Africa (Egypt, Algeria, Morocco, Tunisia, Libya, Sudan, etc.). Swahili is spoken in East Africa (Tanzania, Kenya, Uganda, DRC, etc.). What is the most widely spoken language in Africa?

Russian is the most spoken native language in Europe (about 120 million native speakers). German is second (about 100 million), French third (about 80 million). Russian is spoken in Russia, Belarus, Ukraine, Kazakhstan, and other former Soviet republics. What is the most spoken native language in Europe?

Tamil is one of the oldest living languages in the world, with a recorded history of over 2,000 years. It is still spoken by about 80 million people in South India, Sri Lanka, Singapore, and Malaysia. Sanskrit is an ancient language that is no longer spoken as a native language (used only in religious rituals). What is one of the oldest living languages still spoken today?

Spanish is the most commonly studied foreign language in the United States (about 8 million students). It is also the most spoken second language in the U.S. (over 40 million native Spanish speakers). French is second, followed by German, Italian, Japanese, and Chinese. What is the most studied foreign language in the U.S.?

Climate is the long-term average of weather patterns in a region over decades or centuries. Weather is the short-term condition of the atmosphere (day-to-day). The main factors affecting climate include latitude, altitude, ocean currents, prevailing winds, and proximity to water. What is the difference between weather and climate?

Tropical rainforest climates (Af) are hot and humid year-round, with high rainfall (over 80 inches / 2,000 mm per year). There is no dry season. The Amazon rainforest, Congo Basin, and Southeast Asian rainforests have this climate. Which biome has the highest biodiversity?

Deserts are defined by low precipitation (less than 10 inches / 250 mm per year). They can be hot (Sahara) or cold (Antarctica, Gobi). Deserts have extreme temperature variations between day and night. Which desert is the largest hot desert in the world?

Polar climates (ice cap and tundra) are extremely cold, with average temperatures below freezing for most of the year. The tundra has permafrost (permanently frozen ground). Which biome has permafrost and low-growing plants (mosses, lichens, shrubs)?

Grasslands are biomes dominated by grasses rather than trees. They include savannas (tropical grasslands with scattered trees), prairies (temperate grasslands), and steppes (dry grasslands). The savanna is home to large herbivores (zebras, giraffes, elephants) and predators (lions, cheetahs). Which grassland has scattered trees and a wet and dry season?

The Köppen climate classification system is the most widely used system for classifying the world's climates. It was developed by German climatologist Wladimir Köppen in 1884. The five main groups are: tropical (A), dry (B), temperate (C), continental (D), and polar (E). Which climate group has hot, humid summers and mild winters?

The Mediterranean climate (Csa) has hot, dry summers and mild, wet winters. It is found around the Mediterranean Sea, as well as in California, central Chile, southwestern Australia, and the Western Cape of South Africa. Which of these regions has a Mediterranean climate?

Monsoon climates are characterized by seasonal reversal of winds, bringing heavy rainfall in summer (wet season) and dry conditions in winter (dry season). The Indian subcontinent and Southeast Asia experience the most dramatic monsoon. Where are monsoon climates most common?

As altitude increases, temperature decreases (about 3.5°F / 2°C per 1,000 feet / 300 meters). This is why mountains have cooler climates than surrounding lowlands. The tree line is the altitude above which trees cannot grow. What happens to temperature as altitude increases?

Climate change (global warming) is causing shifts in ecosystems, melting glaciers and ice caps, rising sea levels, more frequent extreme weather events, and species migration. The Arctic is warming faster than any other region (Arctic amplification). Which ecosystem is most threatened by climate change?

The Himalayas are the highest mountain range in the world, containing Mount Everest (29,032 feet / 8,849 meters), the highest peak on Earth. The Himalayas were formed by the collision of the Indian and Eurasian tectonic plates. Which mountain range contains Mount Everest?

The Andes Mountains are the longest mountain range in the world, stretching about 4,350 miles (7,000 kilometers) along the western edge of South America, through seven countries: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile, and Argentina. Which mountain range is the longest in the world?

The Rocky Mountains (the Rockies) are the major mountain range in western North America, stretching about 3,000 miles (4,800 kilometers) from British Columbia (Canada) to New Mexico (United States). The Rockies are known for their rugged peaks, forests, and national parks (Yellowstone, Rocky Mountain, Grand Teton). Which mountain range runs through the western United States and Canada?

The Alps are the most famous mountain range in Europe, stretching about 750 miles (1,200 kilometers) across eight countries: France, Switzerland, Italy, Monaco, Liechtenstein, Austria, Germany, and Slovenia. The highest peak is Mont Blanc (15,781 feet / 4,810 meters) on the French-Italian border. Which mountain range is known for its beautiful scenery, skiing, and the Matterhorn?

The Ural Mountains are a mountain range that runs north-south through western Russia, traditionally considered the natural boundary between Europe and Asia. The Urals are about 1,600 miles (2,500 kilometers) long. They are rich in minerals (iron, coal, copper, gold, gemstones). Which mountain range separates Europe from Asia?

The Caucasus Mountains are located between the Black Sea and the Caspian Sea, forming part of the border between Europe and Asia. They contain Mount Elbrus (18,510 feet / 5,642 meters), the highest peak in Europe. Mount Elbrus is the highest mountain in Europe. Which mountain range contains Mount Elbrus?

The Appalachian Mountains are an ancient mountain range in eastern North America, stretching about 1,500 miles (2,400 kilometers) from Alabama (USA) to Newfoundland (Canada). They are much older than the Rockies (about 480 million years old) and have been worn down by erosion. Which mountain range is the oldest in North America?

The Great Dividing Range is the longest mountain range in Australia, stretching about 2,300 miles (3,700 kilometers) along the eastern coast from Queensland to Victoria. It is not very high (highest peak: Mount Kosciuszko at 7,310 feet / 2,228 meters). Which mountain range is the longest in Australia?

The Himalayas are the highest mountain range in the world (Mount Everest). The Andes are the longest mountain range in the world (about 4,350 miles / 7,000 km). Which mountain range is the highest in the world?

The Pyrenees Mountains form the natural border between France and Spain, stretching about 305 miles (491 kilometers) from the Bay of Biscay to the Mediterranean Sea. The highest peak is Pico de Aneto (11,168 feet / 3,404 meters). Which mountain range separates France and Spain?

The Nile River is the longest river in the world, stretching about 4,132 miles (6,650 kilometers). It flows northward through northeastern Africa, passing through 11 countries, and empties into the Mediterranean Sea. The Nile was crucial to the development of ancient Egyptian civilization. Which river is the longest in the world?

The Amazon River is the largest river in the world by volume of water discharged (about 209,000 cubic meters per second). It is also the second-longest river (about 4,000 miles / 6,400 kilometers). The Amazon flows through South America, primarily Brazil, Peru, and Colombia. It discharges into the Atlantic Ocean. Which river carries the most water?

The Yangtze River (Chang Jiang) is the longest river in Asia and the third-longest in the world (about 3,915 miles / 6,300 kilometers). It flows through China from the Tibetan Plateau to the East China Sea. The Three Gorges Dam on the Yangtze is the world's largest hydroelectric power station. Which river is the longest in Asia?

The Mississippi-Missouri River system is the longest river system in North America (about 3,902 miles / 6,275 kilometers). The Mississippi River flows from Minnesota to the Gulf of Mexico. The Missouri River is a tributary of the Mississippi. Which river is the longest in North America?

The Yenisei River is the largest river system flowing into the Arctic Ocean. It is the fifth-longest river in the world (about 3,445 miles / 5,539 kilometers). It flows through Mongolia and Russia (Siberia). Which river is the largest flowing into the Arctic Ocean?

The Congo River is the deepest river in the world (over 720 feet / 220 meters deep in some places). It is also the second-largest river by volume (after the Amazon). It flows through central Africa, primarily the Democratic Republic of the Congo. Which river is the deepest?

The Yellow River (Huang He) is the second-longest river in China (after the Yangtze). It is called the "Cradle of Chinese Civilization" because the earliest Chinese dynasties developed along its banks. The river gets its name from the yellowish silt (loess) it carries. What is the Chinese name for the Yellow River?

The Indus River is the longest river in Pakistan. It flows from the Tibetan Plateau through India and Pakistan to the Arabian Sea. The Indus Valley Civilization (Harappa and Mohenjo-Daro) was one of the world's earliest urban civilizations (c. 2600-1900 BCE). Which river was the cradle of the Indus Valley Civilization?

The Rhine River is one of the most important rivers in Europe. It flows from the Swiss Alps through Germany and the Netherlands to the North Sea. The Rhine is a major transportation route for goods (coal, oil, chemicals). It passes through the famous Rhine Gorge (UNESCO World Heritage site) with its many castles. Which river flows through the Rhine Gorge?

The Danube River is the second-longest river in Europe (after the Volga). It flows through 10 countries: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova, and Ukraine. The Danube flows through four capital cities: Vienna (Austria), Bratislava (Slovakia), Budapest (Hungary), and Belgrade (Serbia). How many capital cities does the Danube flow through?