Unit 1 surveys the major regions of the world around 1200 to 1450, just before the great connecting networks of Unit 2. Its purpose is comparison: by the end you should be able to say how any two of these societies were governed, what held them together, and how they made their living.

Three questions apply everywhere, and answering them for each region is the whole unit:

• How is the state organised? Who rules, through what officials, and paid for how?
• What belief system shapes society? Religion supplies law, education, and legitimacy in every region here.
• What is the economic base? Agriculture almost everywhere, but with very different labour systems and levels of trade.

Song China 宋朝中国 is the unit's benchmark state. Its economy became increasingly commercialized 商业化 while remaining largely agrarian 农业为主, supported by rising productive capacity - Champa rice 占城稻, iron and steel production, and transport improvements such as the expanded Grand Canal 大运河.

Government ran through a bureaucracy 官僚体系 staffed by the civil service examination 科举制度, which recruited officials on merit and gave the state unusual administrative depth.

Chinese cultural traditions continued and influenced neighbouring regions - Korea, Japan, and Vietnam adopted writing, bureaucratic models, and belief systems. Neo-Confucianism 新儒学 shaped society, including filial piety 孝道 and the expectation of women's deference. Buddhism 佛教 continued to shape Asian societies and spread further, in forms including Theravada 上座部佛教, Mahayana 大乘佛教, and Tibetan 藏传佛教 Buddhism.

As the Abbasid Caliphate 阿拔斯哈里发国 fragmented, new Islamic political entities emerged, most of them Turkic 突厥人 in origin - among them the Seljuk Empire 塞尔柱帝国, the Mamluk sultanate of Egypt 埃及马穆鲁克苏丹国, and the Delhi Sultanate 德里苏丹国.

Muslim rule continued to expand across Afro-Eurasia through military expansion, merchant activity 商人活动, and the work of missionaries 传教士, especially Sufis 苏非派, whose adaptable practice helped Islam spread.

Muslim states encouraged significant intellectual innovations and transfers 智识创新与传播: advances in mathematics, medicine, and astronomy, and the preservation and extension of Greek learning that later moved into Europe.

Hinduism 印度教, Islam, and Buddhism continued to shape the region, and their meeting produced new devotional forms - the bhakti movement 巴克提运动 in Hinduism and Sufism in Islam, both emphasising direct personal devotion.

State formation showed the unit's theme of continuity and diversity: the Delhi Sultanate ruled much of the north, Vijayanagara 维查耶纳伽尔 arose in the south, and in Southeast Asia the sea-based Majapahit 满者伯夷 and the land-based Khmer Empire 高棉帝国 organised power in different ways.

In the Americas, state systems showed continuity, innovation, and diversity: the Maya 玛雅 city-states, the Mexica 墨西加人 (Aztec) with tribute-based expansion, and the Inca 印加 with a centralised administration, labour obligation, and road system.

In Africa, state systems likewise varied: Great Zimbabwe 大津巴布韦 grew on gold and cattle, Ethiopia 埃塞俄比亚 was a long-established Christian kingdom, and the Hausa Kingdoms 豪萨城邦 sat on trans-Saharan trade routes.

Europe was politically fragmented 政治上分裂, characterised by decentralised monarchies and by feudalism 封建制度 - a system of land held in exchange for service. Monarchs slowly consolidated power, but nothing here approached the administrative reach of Song China.

Christianity 基督教, Judaism 犹太教, and Islam all shaped European society, with the Church supplying law, learning, and legitimacy.

Europe was largely agricultural, dependent on free and coerced labour 自由与强制劳动, including serfdom 农奴制.

The unit's reasoning skill is comparison 比较. The productive comparisons are structural rather than evaluative:

• Centralised administration (Song China, Inca) against fragmented or decentralised rule (Europe, post-Abbasid Islamic states).
• Recruitment by examination against recruitment by birth.
• States funded by tribute (Mexica) against states funded by taxation (Song China).

Worked example (a real AP exam question). AP World short-answer questions regularly ask students to "Identify one similarity" or "Explain one difference" between two regions in a period. A full-mark answer for this unit names the feature and applies it to both: "Both Song China and the Inca Empire used a centralised bureaucracy to govern a large territory, but Song China recruited officials through a competitive examination system while the Inca staffed administration through hereditary elites and a labour obligation." Notice the shape: a comparison must be one feature, two societies. Describing each society in turn and leaving the reader to infer the comparison does not earn the point.

• Learn each region through the same three questions - state, belief system, economy - so any comparison question already has a structure.
• Song China is the benchmark: examination-based bureaucracy, commercialised agriculture, and cultural influence on neighbours.
• For Dar al-Islam, remember the pattern is fragmentation into new states plus continued expansion by trade and Sufi missionaries.
• Give a named state for the Americas and Africa. Mexica tribute, Inca labour obligation, Mali and Great Zimbabwe gold are the reliable examples.
• Europe's distinguishing features are fragmentation, feudalism, and coerced agricultural labour.
• Write comparisons as one feature across two societies, never as two separate descriptions.

Unit 2 covers the three great exchange networks of 1200 to 1450 - the Silk Roads, the Indian Ocean, and the trans-Saharan routes - and asks the same question of each: what made trade grow, and what did that growth change?

Growth had three common causes, and naming them is worth more than listing goods:

• Improved commercial practices 商业惯例的改进 - money economies 货币经济, credit 信贷, and forms of partnership that spread risk.
• Improved transportation technologies 交通技术的改进 - better ships, saddles, and navigation.
• State support 国家支持 - empires that secured routes and taxed the trade benefited from protecting it.

Demand mattered too: luxury goods 奢侈品 from Chinese, Persian, and Indian artisans found expanding markets across Afro-Eurasia, and producers increased output to meet that demand.

The Silk Roads 丝绸之路 carried high-value, low-bulk goods overland across Eurasia: silk, porcelain, spices, and precious metals.

Its enabling innovations were commercial as much as technical - caravanserai 商队旅馆 along the routes, the use of paper money 纸币 and bills of exchange 汇票 in China, and forms of credit that let merchants trade without carrying bullion.

The consequence for producers: Chinese artisans expanded output, and cities along the routes grew wealthy on the traffic passing through.

Empires collapsed and were reconstituted in this period, and the largest transformation came from the Mongol Empire 蒙古帝国.

Mongol expansion facilitated Afro-Eurasian trade and communication by bringing much of the network under a single authority, which lowered the risk of long-distance travel - a period often called the Pax Mongolica 蒙古和平.

Interregional contacts and conflicts also encouraged technological and cultural transfers 技术与文化传播: gunpowder technology moved west, Chinese administrative and medical knowledge circulated, and scholars and craftsmen were relocated across the empire.

The Mongols illustrate the unit's central irony: conquest and destruction produced the conditions for exchange.

The Indian Ocean network moved bulkier goods than the Silk Roads - textiles, timber, grain, and spices - because ships carry more than camels.

Its enabling technologies were maritime: knowledge of the monsoon winds 季风, the lateen sail 三角帆, the dhow 单桅帆船, and navigational tools including the compass 罗盘 and astrolabe 星盘.

Its consequences are the most examinable in the unit:

• The network fostered the growth of states 促进国家成长, such as the Swahili city-states on the East African coast and Srivijaya and Majapahit in Southeast Asia.
• Merchants established diasporic communities 侨居社群 in key ports, introducing their own culture while adopting local ways.
• Long-distance trade depended on and expanded coerced labour and on the movement of people as well as goods.

The trans-Saharan routes crossed the desert on innovations in existing technology - above all the camel saddle 骆驼鞍 and organised caravans 商队.

Gold from West Africa moved north and salt 盐 moved south. The expansion of empires, including Mali 马里帝国, facilitated Afro-Eurasian trade by securing the routes and taxing them - and Mali's wealth and its ruler's famous pilgrimage advertised the region across the Islamic world.

Increased cross-cultural interaction produced diffusion 传播 of literary, artistic, scientific, and religious traditions - the spread of Islam along trade routes, Buddhist and Neo-Confucian influence in East Asia, and the movement of scientific and mathematical knowledge.

An increasing number of travellers 旅行者 moved within and between regions, and their accounts are the period's key evidence.

The fate of cities varied: some declined as routes shifted or invasions came, while others grew into major commercial centres.

The environmental consequences were as large as the cultural ones. There was continued diffusion of crops and pathogens 作物与病原体的传播, and epidemic disease travelled with trade - most catastrophically the Black Death 黑死病, which moved along the same routes that carried goods and killed a large share of the population of Afro-Eurasia.

The unit's reasoning skill is comparison. Compare the networks on what they carried, what made them possible, and what they changed - not on which was "most important".

Worked example (a real AP exam question). AP World short-answer questions frequently ask students to "Explain one similarity" or "Explain one difference" between two trade networks in this period. A full-mark answer names the feature and applies it to both, then explains: "Both the Silk Roads and the Indian Ocean network expanded because of improved commercial practices, but the Indian Ocean carried heavier, lower-value goods such as timber and grain because ships could transport far greater bulk than overland caravans." Notice the shape: the because clause is what turns a difference into an explanation, and without it the answer only describes.

• Explain growth with the three causes - commercial practices, transport technology, state support - rather than listing trade goods.
• Match cargo to carrier: overland routes move high-value, low-bulk goods; maritime routes move bulk.
• Learn the enabling technologies by network: caravanserai and credit; monsoons, lateen sail and dhow; the camel saddle.
• The Mongols' examinable role is facilitating exchange, not conquest for its own sake.
• The Black Death is the environmental consequence to name, and it travelled on the trade network itself.
• On difference questions, always add the because. A stated difference without a cause is only half an answer.

Unit 3 covers the great land-based empires 陆基帝国 of roughly 1450 to 1750. Four questions organise it: how they expanded, how they governed, how they paid for themselves, and how they used religion.

Expansion relied on the increased use of gunpowder, cannons, and armed trade 火药、火炮与武装贸易 - which is why these are often called the gunpowder empires 火药帝国. Access to gunpowder weapons let a central ruler overpower regional rivals and fortified nobles, so military technology and political centralisation grew together.

The empires to know:

• The Manchu (Qing) 满清 in Central and East Asia.
• The Mughal 莫卧儿 in South Asia.
• The Ottoman 奥斯曼 in the eastern Mediterranean and beyond.
• The Safavid 萨法维 in Persia.

Rulers faced the same problem: how to control territory far from the capital. The CED names the tools they used.

Recruitment of bureaucratic elites 官僚精英的选任 and the development of military professionals 职业军人 gave rulers officials who owed their position to the state rather than to birth. The clearest case is the Ottoman devshirme 德夫希尔梅 system, which recruited and trained administrators and soldiers, including the janissaries 耶尼切里; the Manchu continued China's examination system; the Safavids used ghulams 古拉姆.

Revenue came through tribute collection 纳贡, tax farming 包税制, and innovative tax-collection systems. The Mughal zamindar 柴明达尔 system and Ottoman tax farming are the standard examples, and the Ming practice of collecting taxes in hard currency 硬通货 is another.

Rulers continued to use religious ideas, art, and monumental architecture 宗教观念、艺术与纪念性建筑 to legitimise their rule - Mughal mosques and mausolea, Ottoman mosque complexes, Qing imperial portraits, and European palaces such as Versailles all do the same work.

Religious change also produced conflict:

• The Protestant Reformation 新教改革 marked a break with existing Christian traditions and led to sustained religious and political conflict in Europe.
• Political rivalry between the Ottoman and Safavid empires intensified the Sunni-Shia split 逊尼派与什叶派分裂, showing how state rivalry can deepen a religious division.
• Sikhism 锡克教 developed in South Asia in a context of interaction between Hinduism and Islam.

Political and religious disputes together produced rivalries and conflict between states 国家之间的对抗与冲突 across Eurasia.

The unit's reasoning skill is comparison, and the productive comparisons are about method, not size:

• Recruiting officials by examination (Qing) against by enslaved-elite systems (Ottoman devshirme, Safavid ghulams).
• Tax farming (Ottoman) against land-revenue intermediaries (Mughal zamindars) against direct taxation (Ming hard currency).
• Legitimacy through religious identity (Safavid Shi'ism as state religion) against through tolerance of diversity (Mughal policy under Akbar).

Worked example (a real AP exam question). AP World short-answer questions in this unit typically ask students to "Explain one similarity" or "Explain one difference in how land-based empires maintained power." A full-mark answer names the method for both and explains the effect: "Both the Ottoman and Mughal empires used intermediaries to collect revenue rather than salaried tax officials, but the Ottomans used tax farming, which sold the right to collect for a fixed payment, while the Mughals relied on zamindars, hereditary landholders whose local standing gave them a permanent interest in the countryside." Notice the shape: the comparison is one function (raising revenue), performed two ways, with the consequence stated.

• Say why gunpowder mattered: it let central rulers overpower regional rivals, so military change and centralisation go together.
• Learn the four empires by their administrative method, not their territory - devshirme, examinations, zamindars, ghulams.
• Tax farming sells the right to collect; a zamindar is a hereditary landholder. Questions turn on that difference.
• Monumental architecture is evidence of legitimation, not decoration. Say what it was doing.
• The Ottoman-Safavid rivalry is the example of political conflict deepening a religious divide.
• Comparisons should be one function performed two ways, with the consequence stated.

Unit 4 covers 1450 to 1750 - the period in which the Eastern and Western Hemispheres are permanently joined, and the consequences of that joining.

The voyages rested on borrowed knowledge. Learning and technology from the Classical, Islamic, and Asian worlds was gathered and applied in Europe: new tools, innovations in ship design 船舶设计, and better understanding of navigation 航海 - the caravel 卡拉维尔帆船, the astrolabe, the magnetic compass, and knowledge of wind patterns.

State-supported maritime exploration 国家支持的海上探索 then followed:

• Portuguese development of maritime technology and navigational skill led to the sea route around Africa to the Indian Ocean.
• Spanish sponsorship of Columbus and subsequent voyages opened the Atlantic to the Americas.
• English, French, and Dutch crossings of the northern Atlantic followed.

Motives combined the search for wealth, competition between states, and religious mission.

New connections between the hemispheres produced the Columbian Exchange 哥伦布大交换, and the CED spells out four consequences.

• European colonisation led to the unintentional transfer of disease 疾病的非蓄意传播 to the Americas, causing catastrophic population loss.
• American foods 美洲作物 - maize, potatoes, cassava - became staple crops in parts of Europe, Asia, and Africa.
• Afro-Eurasian fruit trees, grains, sugar, and domesticated animals 驯化动物 were brought to the Americas, reshaping its landscapes and economies.
• Populations in Afro-Eurasia benefited nutritionally 营养状况改善 from a more diverse diet, contributing to population growth.

The asymmetry is the examinable point: the same exchange raised population in Afro-Eurasia and destroyed it in the Americas.

Europeans established trading posts 商站 in Africa and Asia, which proved profitable, and pursued colonisation in the Americas driven by political, religious, and economic rivalries 对抗.

Where existing states were strong, Europeans traded rather than conquered: despite disruption caused by Portuguese arrival, existing trade networks in the Indian Ocean continued 印度洋既有贸易网络得以延续, and Asian states largely dictated the terms.

In the Americas the pattern was different. Colonial economies depended on agriculture and on coerced labour 强制劳动:

• Enslavement in Africa continued in its traditional forms, including incorporation into households.
• The growth of the plantation economy 种植园经济 increased demand for enslaved labour, and the Atlantic slave trade expanded enormously to supply it.
• Systems such as the encomienda and mita 米塔制 compelled Indigenous labour.

Mercantilist 重商主义 policies were used by European rulers to expand and control their economies: colonies existed to supply raw materials and buy finished goods, and trade was directed through the mother country.

The Atlantic trading system 大西洋贸易体系 moved goods, wealth, and people between Europe, Africa, and the Americas - the pattern usually taught as triangular trade, though real routes were more complex.

Economic disputes led to rivalries and conflict between states, and commercial competition became a standing cause of European war.

Colonial societies developed new social hierarchies 社会等级, defined by ancestry and by place of birth - the Spanish casta system being the most formally codified.

Rulers everywhere faced resistance. Enslaved people resisted through rebellion 起义 and maroon communities 逃奴社群; Indigenous peoples resisted colonial demands; peasants and religious groups challenged state power across Eurasia.

The unit's reasoning skill is continuity and change. The strongest answers hold both: connection between hemispheres was genuinely new, while the dominance of agriculture, coerced labour, and land empires continued.

Worked example (a real AP exam question). AP World short-answer questions in this unit ask, for example, to "Explain one effect of the Columbian Exchange on the Americas" and "…on Afro-Eurasia." A full-mark pair states the effect and the mechanism for each: "In the Americas, transferred diseases such as smallpox caused a demographic collapse, which created the labour shortage that European colonisers met by expanding the Atlantic slave trade. In Afro-Eurasia, American crops such as the potato and maize improved nutrition and contributed to population growth." Notice the shape: effect questions want the consequence traced, and the two halves must not be the same answer twice.

• Explain the voyages with borrowed technology plus state support, not with individual explorers.
• Keep the Columbian Exchange two-directional and asymmetrical: population fell in the Americas and rose in Afro-Eurasia.
• Where Asian states were strong, Europeans traded; where disease had shattered societies, they conquered. That contrast answers many questions.
• Mercantilism is the policy, the Atlantic system is the flow, and coerced labour is what made the plantation economy work.
• Always include resistance - rebellion, maroon communities, Indigenous refusal - since it is examinable and often omitted.
• On effect questions, trace the consequence. A named change with no mechanism is only half the mark.

Unit 5 covers 1750 to 1900, and it has two engines running at once: an intellectual revolution that changed how people justified political authority, and an industrial revolution that changed how societies produced and lived. Most questions ask you to connect them.

Enlightenment 启蒙运动 philosophies applied new ways of understanding and empirical approaches 实证方法 to both the natural world and human relationships. From that came ideas that questioned established traditions:

• Individualism 个人主义, natural rights 天赋权利, and the social contract 社会契约.
• Calls for religious tolerance 宗教宽容 and limits on established authority.

Those ideas influenced reform movements 改革运动: the expansion of suffrage, the abolition of slavery, and demands for women's suffrage 妇女选举权诉求 alongside an emergent feminism 女权主义 that challenged political and gender hierarchies.

Nationalism 民族主义 became a major force shaping historical developments. People developed a new sense of commonality 共同体意识 based on language, religion, social customs, and territory, and these newly imagined national communities were often linked to state-building.

Discontent with monarchist and imperial rule encouraged revolution 革命. Enlightenment ideas, as reflected in revolutionary documents, justified those movements, and colonial subjects in the Americas led a series of rebellions inspired by them - the examinable set being the American, French, Haitian, and Latin American revolutions.

The pattern to hold: an idea (rights, consent, nation) plus a grievance (taxation, exclusion, slavery, colonial rule) produces a movement. Answers that give only the idea, or only the grievance, explain nothing.

A variety of factors contributed to the growth of industrial production: access to coal 煤炭 and iron 铁, navigable rivers and canals, agricultural productivity 农业生产率 that freed labour, capital 资本 and legal protection for it, urbanisation, and access to raw materials and markets through overseas empire.

The factory system 工厂制度 concentrated production in a single location under supervision, replacing dispersed household production. That change - as much organisational as technical - is what made the scale of output possible.

The rapid development of steam-powered 蒸汽动力 industrial production in Europe spread to other regions, and as new methods became common, states that industrialised gained enormous advantages in wealth and military power over those that did not.

Technology compounded the change: the steam engine 蒸汽机 and later the internal combustion engine 内燃机; the second industrial revolution 第二次工业革命 in steel, chemicals, and electricity; and railroads 铁路, steamships 蒸汽船, and the telegraph 电报, which made exploration, colonisation, and administration at a distance possible.

As industrial influence grew, a small number of states sponsored industrialisation 国家推动工业化 directly - the standard examples being Meiji Japan, Russia under state-led programmes, and Egypt under Muhammad Ali.

Western European countries began abandoning mercantilism and adopting free trade 自由贸易 policies, and the global nature of trade and production contributed to the proliferation of transnational businesses 跨国企业 and new financial instruments.

Reaction came from several directions:

• Workers organised, often in labour unions 工会, and pressed for shorter hours, safety, and wages.
• Alternative visions of society emerged - socialism 社会主义, communism 共产主义, and anarchism 无政府主义 - as critiques of industrial capitalism.
• Some governments passed reform legislation 改革立法 on working conditions, child labour, and public health.
• The expansion of industrialising states led to internal reform movements 内部改革运动 elsewhere in Asia, as states tried to respond to new pressure.

New social classes 社会阶级 formed, including a middle class 中产阶级 and an industrial working class 工业工人阶级, each with its own culture and politics.

Other changes are examinable: rapid urbanisation 城市化 with overcrowding and disease; changes in family structure 家庭结构 and in women's work as production left the home; and rising standards of living 生活水平 over the long run, unevenly distributed and reached only after decades of hardship.

The unit's reasoning skill is continuity and change. Production and class structure changed fundamentally, while imperial competition, coerced labour in colonised regions, and inequality persisted in new forms.

Worked example (a real AP exam question). AP World short-answer questions here ask, for example, to "Explain one way in which industrialisation changed social structures" between 1750 and 1900. A full-mark answer names the change and traces it: "Industrialisation created a large industrial working class, because the factory system concentrated production in single locations and drew rural labourers into cities to work for wages, replacing household production and the rural social order that depended on it." Notice the shape: explain requires the mechanism - factory system, urban migration, wage labour - not just the statement that new classes appeared.

• Answer "why Britain first" with several factors at once - coal, capital, agriculture, empire - not one cause.
• The factory system is an organisational change; say what it replaced.
• For revolutions, pair an idea with a grievance. Either alone explains nothing.
• State-sponsored industrialisation (Meiji Japan, Russia, Egypt) is the contrast to the British pattern.
• Give the reactions as a set: unions, socialism and communism, and reform legislation.
• Living standards rose eventually and unevenly. Saying so is what makes an answer an evaluation.

Unit 6 covers the consequences of industrialisation, 1750 to 1900: why industrial states expanded, how people resisted, how the world economy reorganised, and who moved.

A range of cultural, religious, and racial ideologies 文化、宗教与种族意识形态 were used to justify imperialism. The examinable ones are the civilising mission 文明教化使命, missionary activity, Social Darwinism 社会达尔文主义 applied to nations and peoples, and nationalism - the claim that colonies proved a state's greatness.

These are justifications, not causes. Naming them as ideology, and separating them from the economic and strategic motives in the next sections, is what a strong answer does.

Expansion took several forms, and the CED distinguishes them:

• Some states strengthened control over existing colonies, converting trading relationships into direct rule.
• European states, the United States, and Japan acquired new territory, showing that imperialism was not only European.
• Many European states used both warfare and diplomacy 战争与外交 to expand - conquest, but also treaties, protectorates, and partition agreements made in Europe.
• Europeans established settler colonies 定居殖民地 in some places, which displaced Indigenous populations far more thoroughly than administrative rule.
• The United States, Russia, and Japan expanded by taking contiguous land rather than overseas territory.

Anti-imperial resistance 抵抗 took various forms, and listing only armed revolt loses marks:

• Direct resistance 直接抵抗 - armed rebellion against colonial authority.
• Creation of new states 建立新国家 by leaders organising against imperial power.
• Religious and cultural movements 宗教与文化运动 that reasserted local identity against colonial rule.

Increasing questions about political authority and growing nationalism in colonised regions led to rebellions, some of which were sustained enough to change imperial policy. The important point: resistance is continuous throughout the period, not a late reaction.

The need for raw materials 原材料 for factories and increased food supplies 粮食供应 for growing urban populations reorganised production across the world. Colonies and dependent regions were pushed toward cash crops 经济作物 and extractive industries 采掘业, often at the cost of food production for local use.

Economic imperialism 经济帝国主义 is the examinable distinction. Industrialised states and their businesses exercised control through investment, loans, and trade dominance 投资、贷款与贸易支配 without necessarily taking political control - so a region could be economically dominated while remaining formally independent.

Trade in some commodities was organised so that merchants and firms in industrialised states held disproportionate power 不成比例的权力 over producers, setting prices and terms.

Migration in this period was shaped by demographic change in both sending and receiving societies, and by new modes of transportation 交通方式 - steamships and railways - which made long-distance and often temporary or seasonal 临时或季节性 movement possible for the first time.

Two kinds must be distinguished:

• Many people chose freely to relocate, usually in search of work.
• The global capitalist economy continued to rely on coerced and semi-coerced labour 强制与半强制劳动, including indentured servitude 契约劳工 and convict labour, after the legal end of the slave trade.

Three effects are named directly in the CED:

• Migrants tended to be male, leaving women to take on new roles 女性承担新角色 in the home societies they left.
• Migrants created ethnic enclaves 族裔聚居区 in destination societies, transplanting and adapting their cultures.
• Receiving societies did not always embrace immigrants, and the examinable evidence is legal exclusion - most clearly the restriction of Chinese and other Asian migration in several countries.

The unit's reasoning skill is causation. The strongest chain: industrial production created demand for raw materials and markets, which drove expansion; expansion required justification, which ideology supplied; and both produced resistance and mass migration.

Worked example (a real AP exam question). AP World short-answer questions here ask, for example, to "Explain one way in which industrialisation contributed to imperialism" between 1750 and 1900. A full-mark answer traces the mechanism: "Industrial factories required raw materials such as cotton and rubber that could not be produced in Europe, so industrial states took political or economic control of regions that could supply them, reorganising those economies around export crops." Notice the shape: the mark is for the link, not for asserting that industrialisation and imperialism are connected.

• Separate justifications (civilising mission, Social Darwinism) from causes (raw materials, markets, strategy). Questions often ask for one and reward not confusing it with the other.
• Economic imperialism works without political control; that distinction answers many questions on its own.
• Give three kinds of resistance - direct, new states, religious and cultural movements.
• Migration questions want the split between free and coerced or semi-coerced movement.
• For effects, use the CED's own three: male migration changing home societies, ethnic enclaves, and exclusion laws.
• Causation answers must trace a mechanism. Asserting a connection is not explaining one.

Unit 7 covers global conflict from 1900, and its organising question is not "what happened in the wars" but why the political order that existed in 1900 collapsed, and what replaced it.

At the start of the century the West dominated the global political order. Over the following decades both land-based and maritime empires gave way to new states, and the CED names the mechanism as a combination of internal and external factors 内外因素.

• The older land-based Ottoman, Russian, and Qing empires collapsed under that combination - internal strain and pressure from outside at the same time.
• States around the world challenged the existing political and social order, and the CED's named case is the Mexican Revolution 墨西哥革命, which arose from political and economic inequality.

The examinable habit here is pairing. An answer that gives only internal weakness, or only external pressure, has given half the explanation.

The CED compresses the causes into one statement, and every element of it is worth marks:

• Imperialist expansion 帝国主义扩张 and competition for resources 资源竞争.
• Territorial and regional conflicts 领土与地区冲突.
• A flawed alliance system 结盟体系 that turned a local conflict into a general one.
• Intense nationalism 极端民族主义.

Notice the shape of the claim: the first three supply the tension, and the alliance system supplies the escalation 升级. That distinction - between what made conflict likely and what made it global - is the single most useful thing to hold from this topic.

World War I was the first total war 总体战. The CED lists the methods governments used, and they are not only military:

• Political propaganda 政治宣传, art, and media to sustain public support.
• Intensified forms of nationalism 强化的民族主义.
• Mobilisation of economies and populations 经济与人口动员 - conscription, war production, and the direction of labour.
• Recruitment and use of colonial subjects 殖民地臣民 as soldiers and labourers.

Alongside this, new military technology led to increased levels of wartime casualties 伤亡. The technological point and the mobilisation point are separate marks, so give both.

Following World War I and the onset of the Great Depression 大萧条, governments began to take a more active role in economic life 更积极的经济角色. That is the general claim; the CED then supplies contrasting cases of how far that role went.

In the Soviet Union 苏联, the government controlled the national economy through the Five Year Plans 五年计划, implementing repressive policies at significant cost to the population 人口代价 while achieving rapid industrialisation.

The general pattern that makes this comparable across cases: economic crisis increased the state's claim on the economy everywhere, but the extent 程度 differed enormously - from regulation and public works at one end to full state control at the other. Questions about the interwar economy almost always reward that spectrum.

Between the two world wars, Western and Japanese imperial states predominantly maintained control over colonial holdings, and in some cases gained new territory. The hopes for self-determination 民族自决 raised by the peace settlement were largely not met for colonised peoples.

This is the bridge topic: the tensions the settlement left unresolved feed directly into both the causes of the next war and the anti-imperial movements of Unit 8. Naming that link is what makes a continuity answer strong.

The CED again gives a compound cause, and each element is examinable:

• The unsustainable peace settlement 和约 after World War I.
• The global economic crisis 全球经济危机 produced by the Great Depression.
• Continued imperialist practices 帝国主义行径.
• The rise of fascism and extreme nationalism 法西斯主义与极端民族主义.

Compare this with the World War I list and a real pattern appears: economic pressure and nationalism are common to both, while the specific additions in 1939 are the failed settlement and the new ideological regimes. A comparison question wants exactly that structure - shared causes named, then the differences.

World War II was also a total war, and governments used the same broad categories of method: propaganda, art and media, intensified nationalism, and the mobilisation of economies and populations including colonial subjects.

What changed was the technology and its scale. New military technology and new tactics - including the atomic bomb 原子弹, fire-bombing, and the waging of total war - led to increased levels of casualties, including a far higher proportion of civilian 平民 deaths than in the previous conflict.

The examinable comparison is therefore: methods largely similar, scale and technology different. An answer that says only "both were total wars" has not compared them; an answer that says only "the second was more destructive" has not explained why.

This topic asks for causes and consequences of mass atrocities 大规模暴行 in the period from 1900 to the present. The CED's framing is that the rise of extremist groups in power 极端主义团体 led to the attempted destruction of specific populations, and it names the Holocaust 犹太人大屠杀 - the Nazi killing of Jewish people - as the principal case, alongside other twentieth-century genocides and mass killings.

Handled as history, the examinable content is the pattern: an extremist regime takes state power, defines a population as outside the political community, and uses the machinery of the modern state - bureaucracy, transport, communication - to carry out destruction on a scale earlier regimes could not achieve. That last point connects this topic to the technology theme running through the whole unit.

The unit's reasoning skill is causation, and specifically the relative significance 相对重要性 of causes. That word "relative" is the whole task: you are not listing causes, you are ranking them and defending the ranking.

Worked example (a real AP exam question). AP World short-answer questions in this unit ask, for example, to "Explain one similarity between the ways governments conducted World War I and World War II." A full-mark answer names the similarity and supports it with specifics from both: "Both wars were total wars in which governments mobilised entire economies and populations. In both, states used propaganda and media to sustain public support, directed industrial production toward war material, and recruited soldiers and labourers from their colonies." Notice the requirement: a similarity claim must be evidenced on both sides. Evidence from one war only cannot demonstrate a similarity.

• For the collapse of the Ottoman, Russian, and Qing empires, always pair internal strain with external pressure. One alone is half an answer.
• Separate what made World War I likely (imperial competition, nationalism, regional conflict) from what made it global (the alliance system).
• Total war has a checklist: propaganda, nationalism, economic mobilisation, colonial recruitment. Use it for both wars and the comparison writes itself.
• The interwar economy is a spectrum of state involvement, not a single policy. Say how far a state went, not just that it intervened.
• Comparison questions need evidence on both sides. A detail about only one case cannot support a similarity or a difference.
• "Relative significance" means rank and justify. A list of causes with no argument about which mattered most does not answer the question asked.

Unit 8 covers the period after 1945, and two processes run through it at once: a global ideological rivalry and the end of empire. Most of the unit's questions turn on how those two interacted.

Hopes for greater self-government were largely unfulfilled after World War I. In the years following World War II, increasing anti-imperialist sentiment 反帝情绪 built momentum in colonised regions, and this time it produced independence rather than promises.

At the same time, the technological and economic gains 技术与经济收益 made during World War II by the victorious nations shifted the global balance of power 全球权力平衡. This is the historical context the CED asks for: the war did not just destroy, it redistributed capability.

The shifted balance rapidly evolved into the Cold War 冷战 - a rivalry between the democracies led by the United States and the communist states led by the Soviet Union, conducted as an ideological struggle 意识形态斗争 rather than direct war between the two principals.

The CED insists that this was not a world of only two options. Groups and individuals - including the Non-Aligned Movement 不结盟运动 - opposed and promoted alternatives to the existing economic, political, and social order. Leaving the non-aligned states out of an answer describes a two-sided world that did not exist.

The rivalry produced concrete institutions and conflicts:

• New military alliances 军事同盟 - NATO 北约 and the Warsaw Pact 华沙条约组织.
• Nuclear proliferation 核扩散 - the spread of nuclear weapons to more states.
• Proxy wars 代理人战争 between and within states, in which the two blocs supported opposing sides in conflicts elsewhere rather than fighting each other directly.

The comparison this topic sets up is how each superpower maintained influence over other states - through alliances, aid, military support, and intervention. Both used all four, which is why the comparison question is answerable in both directions.

Two examinable threads run here. First, China: as a result of internal tension 内部矛盾 and Japanese aggression 日本侵略, Chinese communists seized power, and the CED notes this eventually contributed to communist revolutions elsewhere.

Second, state control of the economy. As in the Soviet Five Year Plans of Unit 7, the Chinese government controlled the national economy through the Great Leap Forward 大跃进, implementing repressive policies with significant costs to the population. The CED presents these as a matched pair, which is exactly how a comparison question will ask for them.

Beyond these, movements to redistribute land and resources 土地与资源再分配 developed within states in Africa, Asia, and Latin America, some advocating communism or socialism and some not. That distinction matters: land reform is not the same claim as revolution, and the CED separates them.

Nationalist leaders and parties 民族主义领袖与政党 in Asia and Africa sought varying degrees of autonomy within, or independence from, imperial rule. The examinable set of examples includes the Indian National Congress, Ho Chi Minh in French Indochina, Kwame Nkrumah in the Gold Coast, and Gamal Abdel Nasser in Egypt.

After World War II, some colonies negotiated their independence 通过谈判独立 while others achieved it through armed struggle 通过武装斗争. India and the Gold Coast are the standard negotiated cases; Angola, Vietnam, and Algeria the standard armed ones.

A third strand is easily missed: regional, religious, and ethnic movements challenged both colonial rule and the inherited imperial boundaries 沿袭的帝国边界 those empires left behind. Those boundaries are the reason so many post-independence conflicts were about borders rather than about the departing power.

The redrawing of political boundaries after colonial withdrawal led to the creation of new states, and in some cases to conflict, population displacement, and resettlement 人口流离与重新安置. The partition of British India is the standard case of all three at once.

Economically, governments in newly independent states often took a strong role in guiding economic life to promote development 主导经济以推动发展 - a continuity with the interwar pattern of Unit 7, arrived at from a completely different direction.

There was also a reverse flow of people: the migration of former colonial subjects to imperial metropoles 宗主国 - usually to major cities - which maintained cultural and economic ties between the former colony and the former colonial power long after independence.

Although conflict dominated much of the twentieth century, many individuals and groups - including states - opposed that trend. The CED names three distinct patterns, and they should not be blurred:

• Groups and individuals challenged the wars of the century, and some - Mohandas Gandhi 甘地, Martin Luther King Jr. 马丁·路德·金, and Nelson Mandela 曼德拉 - promoted non-violence 非暴力 as a method of change.
• Militaries and militarised states often responded to the proliferation of conflicts in ways that further intensified them.
• Some movements used violence against civilians in an effort to achieve political aims.

Both the third and second points are examinable content, not asides. A question on "reactions to existing power structures" expects the full range, not only the non-violent one.

The CED gives a compound cause here too: advances in United States military and technological development, the Soviet Union's costly and ultimately failed invasion of Afghanistan 阿富汗战争, public discontent 公众不满, and economic problems 经济困难 within the Soviet system.

Notice that three of the four are internal to the Soviet Union. An answer that explains the end of the Cold War purely as external pressure has missed the CED's own weighting.

The unit's reasoning task is to explain the extent to which the effects of the Cold War were similar in the Eastern and Western Hemispheres. "Extent" is a comparison word: it asks for similarity and difference, with a judgement about which dominates.

Worked example (a real AP exam question). AP World short-answer questions here ask, for example, to "Explain one difference between the processes of decolonisation in two different regions after 1945." A full-mark answer names both cases and the difference between them: "In the Gold Coast, independence was achieved largely through negotiation, as nationalist parties won elections and Britain transferred power without a war. In Algeria, independence came through a prolonged armed struggle against France, which left the new state with a military-led government and a devastated economy." Notice what earns the mark: the difference is stated in terms that apply to both cases, and each side carries its own evidence.

• The Cold War was not two-sided. The Non-Aligned Movement is examinable content, and including it lifts an answer immediately.
• Give the effects as the CED does: alliances, nuclear proliferation, proxy wars. Three named effects beat one described at length.
• Negotiated versus armed independence is the highest-value comparison in the unit, because it explains what the new state inherited.
• Inherited imperial boundaries explain post-independence conflict better than any other single factor. Use the phrase.
• For resistance, give all three CED patterns - non-violence, militarised response, and violence against civilians.
• The end of the Cold War was mostly internal to the Soviet system. Weight the causes that way and say why.

Unit 9 covers 1900 to the present, and its central move is evaluative rather than narrative: almost every development it names produced both a benefit and a cost, and questions reward answers that hold both.

The CED names the advances directly:

• New modes of communication 通信方式 - radio, cellular technology, and the internet.
• Energy technologies 能源技术, including the use of petroleum 石油 and nuclear power 核能.
• Medical innovations 医学创新, including vaccines 疫苗 and antibiotics 抗生素, which increased lifespans 寿命.
• The Green Revolution 绿色革命 and commercial agriculture, which increased the global food supply 粮食供应.
• More effective forms of birth control 节育, which gave women greater control over fertility 生育, transformed reproductive practices, and contributed to declining fertility rates in industrialised states.

Note the last one carefully. It is a technological change with a demographic and a social consequence, which makes it unusually useful evidence in questions about the changing role of women.

Diseases, as well as medical and scientific developments, had significant effects on populations across the century. The CED splits the effect in two:

• Diseases associated with poverty persisted 与贫困相关的疾病, while other diseases emerged as epidemics and pandemics 流行病与大流行病.
• Diseases associated with longer lifespans - conditions such as heart disease and neurological illnesses of old age - became more prominent precisely because medical advances extended life.

That second point is the unit's logic in miniature: the success of one intervention produced the conditions for a different problem. It is not a contradiction, and saying so is what makes an answer analytical.

Human activity contributed to deforestation 森林砍伐, desertification 荒漠化, a decline in air quality 空气质量下降, and increased consumption of the world's supply of fresh water 淡水.

The release of greenhouse gases 温室气体 and pollutants into the atmosphere provoked debates about climate change 气候变化. The CED's word is debates - the examinable content is that the science and its policy implications became a subject of international argument, not a settled instruction.

Three developments define the period's economic history, and all three accelerated after 1990:

• Many governments encouraged free-market economic policies 自由市场政策, a trend accelerated by the end of the Cold War.
• Revolutions in information and communications technology led to the growth of knowledge economies 知识经济 in some regions, while other regions remained centred on agriculture or manufacturing.
• Changing economic institutions, multinational corporations 跨国公司, and regional trade agreements 区域贸易协定 reshaped how production and trade were organised across borders.

The continuity worth naming: this is the same story as Unit 6's economic imperialism, in new institutional form. Firms in wealthy states again hold disproportionate influence over the terms on which producers elsewhere participate.

Rights-based discourses 权利话语 challenged old assumptions about race, class, gender, and religion. In much of the world, access to education 受教育机会 and participation in new political and professional roles became more inclusive - an uneven process, but a real one.

At the same time, movements throughout the world protested the inequality of the environmental and economic consequences of global integration 全球一体化. Both halves are examinable: greater inclusion, and organised objection to how the benefits were distributed.

The CED makes three separate claims about culture, and they are not the same claim:

• Political and social changes of the twentieth century led to changes in the arts 艺术 and other forms of cultural expression.
• Arts, entertainment, and popular culture increasingly reflected global influence 全球影响 - forms borrowed, adapted, and recombined across regions.
• Consumer culture 消费文化 became globalised and transcended national borders.

The third is the strongest for essays because it is the most measurable: the same products, brands, and consumption patterns appearing across very different societies.

Responses to rising cultural and economic globalisation took a variety of forms 多种形式. The CED deliberately leaves the category broad, and a good answer fills it with distinct kinds rather than repeating one:

• Movements defending local or national cultural identity 本土文化认同 against homogenising influence.
• Organised opposition to trade agreements and international financial institutions on economic grounds.
• Religious and traditionalist movements 宗教与传统主义运动 rejecting the social changes that accompanied integration.

New international organisations 国际组织, including the United Nations 联合国, emerged to manage problems no single state could handle alone - security, health, refugees, trade, and the environment.

This closes the arc of the course: Unit 7 opened with the collapse of an order and unprecedented conflict; Unit 9 ends with the institutions built in response, and with the argument - still unresolved - about how much authority they should hold.

The unit's reasoning skill is continuity and change, applied across the whole modern period.

Worked example (a real AP exam question). AP World short-answer questions here ask, for example, to "Explain one way in which technological developments after 1900 affected the world's population." A full-mark answer names the development and traces its effect: "Medical innovations such as vaccines and antibiotics reduced deaths from infectious disease, which increased average lifespans and contributed to rapid population growth, particularly in regions where these treatments were introduced faster than birth rates fell." Notice the mechanism: a reason the population changed, not the statement that it did.

• Unit 9 questions are evaluative. For almost every advance, name the benefit and the cost. That single habit lifts most answers here.
• Birth control is technological, demographic, and social evidence at once - unusually flexible in questions about women's changing roles.
• The rise of diseases of longer life is caused by medical success. Say that explicitly; it demonstrates causal reasoning.
• On climate, the CED's word is debates. Write about the argument, not a verdict.
• Connect the global economy back to Unit 6: the same asymmetry, new institutions. Cross-period links score well on essays.
• For resistance to globalisation, give distinct kinds - cultural, economic, religious - not one kind three times.