AP Human Geography — models and processes
AP Human Geography runs on named models: the demographic transition, von Thünen's rings, Christaller's central places, Rostow's stages, Wallerstein's world-systems. Most of the exam is a test of whether you know what each of them actually claims — and, just as often, what it assumes and where it fits the world badly.
Ten questions, covering all seven units. From thinking geographically, what the Mercator projection gives up and why a navigator would accept the trade anyway. From population, reading a stage of the demographic transition off a pair of rates, and reading a country's near future off the age structure of its population — that second one gives real percentages, so the dependency ratio is something you work out rather than something you are told. From migration, the difference between a factor that makes someone leave and a barrier they meet on the way. From cultural patterns, what makes diffusion relocation rather than expansion. From political geography, what the word nation-state actually requires. From agriculture, what orders von Thünen's rings. From cities, what central place theory claims, and what the process of gentrification consists of and whom it moves.
The development question sets Rostow against Wallerstein and does not pick a winner. The difference it turns on is where each account locates the cause: one inside the country, in savings and investment and a leading sector; the other between countries, in a division of labour where a peripheral position exists because a core one does. Geographers argue about which is more useful. The exam asks what each claims.
The same discipline runs through the migration and urban questions. They ask what a process consists of and whom it affects, never which outcome anyone should prefer. Where a model's limits matter, the explanation says so — and where a number cannot answer a question, as with whether a large young cohort becomes an economic advantage, it says that too.
Zestly is an independent study tool. It is not affiliated with the College Board, which owns the AP examinations, and it is not an exam centre.
- Say what a named map projection preserves and what it sacrifices, and why a cartographer would still choose it for a particular purpose
- Place a country in a stage of the demographic transition model from its birth and death rates, and explain what the population is doing
- Compute a dependency ratio from an age structure and say what the same cohorts imply for the workforce twenty years later
- Distinguish push and pull factors from intervening obstacles, and relocation diffusion from the kinds of expansion diffusion
- State what von Thunen's rings are ordered by and what Christaller's central place theory claims about the size and spacing of settlements
- Set out the difference between Rostow's stages and Wallerstein's world-systems approach in terms of where each locates the cause, without treating either as correct
- Describe what gentrification consists of and whom it affects, separating description of a process from judgement of it
A country of thirty million people reports that 42 percent of its population is under 15, 55 percent is aged 15 to 64, and 3 percent is 65 or over. Drawn as a population pyramid this gives a very broad base and almost no top. What does the shape imply?
Sample question
A cartographer chooses the Mercator projection for a world map intended for maritime navigation. What trade-off does that choice make?
- It preserves the true distance between all points on the globe, at the cost of accurate compass bearings.
- It preserves accurate compass bearings, so that a constant heading is a straight line on the map, at the cost of badly inflating the relative size of landmasses at high latitudes.
- It spreads distortion evenly across the whole map, so that no single property is preserved and none is badly lost.
- It keeps area proportions accurate for every landmass, at the cost of distorting the shapes of the polar regions.
See the answer
It preserves accurate compass bearings, so that a constant heading is a straight line on the map, at the cost of badly inflating the relative size of landmasses at high latitudes.
Mercator is conformal: it preserves angles, which is why a rhumb line — a course of constant compass bearing — draws as a straight line, and why it was worth using at sea for four centuries. The price is area, and the error grows with latitude, which is how Greenland ends up looking the size of Africa when it is about a fourteenth of it. The first wrong answer states the exact inverse of what the projection does, and is the most common thing said about it. The distance answer describes something no flat map can achieve at all: no projection of a sphere preserves every distance. And the even-distortion answer describes a compromise projection such as Robinson or Winkel tripel — a reasonable choice for a wall map, and the wrong one for navigation, since it preserves nothing exactly.