Describing patterns and distributions on a map

Photographed from space at night, Egypt is a thin, bright ribbon of lights along the River Nile. How would you describe that pattern in words? The ribbon fans out where the river meets the sea in the north, with darkness on either side of it. Two answers come to mind fast. The first, 'it's in Egypt', names a country, but it says nothing about where the lights are. The second, 'people live by the river because they need water', gives a reason, and nobody asked why. Turning a pattern you can see into words that describe it takes three moves, and this video builds them one at a time. That ribbon of light comes back at the end, described properly.

Picture a map of a town's cafes, with most of the dots crowded along the high street and only a few anywhere else. Distribution means how something is spread across an area. The pattern is the shape that spread makes. Pattern words name that shape. Clustered means bunched close together. Dispersed means scattered widely. Linear means in a line, along a river, a coast, a road or a valley. Even and uneven say whether the spread is the same everywhere. Dense and sparse say how crowded it is. Absent matters too, because where something is not is part of the pattern. The cafes, then, are clustered, and linear along the high street, with very few anywhere else. Now one to try. On a map of a valley, villages are strung out along the valley floor, and none sit on the hills either side. Which pattern words fit villages along the valley floor but not on the hills? Linear, because they follow the valley floor. Absent fits the hills, and the whole spread is uneven. Pattern words say what shape. Locating words say where, and the map hands you every one of them. Compass directions place things, using one of the eight points, measured from something named on the map. Continents, oceans, countries and regions name the big areas. On a world map, the Equator, the Tropics and the polar circles are reference lines. On a smaller map, coasts, rivers, and high or low land are reference points. The scale then turns a gap on the map into a distance in kilometres. Take three ways to place a town. One says it is near the river. One says it is above the hills. One says it is twelve kilometres south-west of the capital. Which of the three places the town on the map? The third one, because it gives a compass point and a distance from somewhere named. The other two feel natural but locate nothing, and the same goes for below, left, right and surrounded by.

Before you write a word about a map, read it. Find north, find the Equator, and read the key and the labels. Then check what the question asks about. A question about location wants where things are, not how big they are. Describing a pattern then takes three moves, in order: the trend, the evidence and the anomaly. The trend is the general pattern, said in one sentence. The evidence backs it up from the map, with named places, compass directions, lines of latitude, and figures from the key. The anomaly is the exception, the place that breaks the pattern. This world map is shaded by the percentage of people using the internet, with invented figures. The key has four classes, from over eighty per cent down to under thirty per cent. Over eighty per cent covers North America, Europe, Japan, South Korea and Australia. Fifty to eighty per cent covers most of South America, North Africa, the Middle East and China. Thirty to forty-nine per cent covers India and much of South East Asia. Under thirty per cent covers most of Africa south of the Sahara, and Afghanistan. First, check what the question asks about. It asks for the pattern of use, so the answer says where use is high and where it is low. Start with the trend: one sentence on where use is greatest and where it is least. Pause it there and work it out for yourself. Internet use is highest in the northern hemisphere, across North America and Europe, and lowest in Africa south of the Sahara. A trend like 'it is high in the north' says far less. Naming the hemisphere and the continents makes it precise. One examiner's report on a world-map question like this says only a very small proportion of students gained the third mark. Those who did mainly used the Equator, the northern hemisphere or named countries. So lead with named places, a hemisphere, a continent or a country, never just the north. The evidence hangs on that trend. Over eighty per cent of people use it across North America, Europe, Japan and South Korea. Under thirty per cent do across most of Africa south of the Sahara. Now the third move. One country in the southern hemisphere sits in a surprising class. Which country breaks the pattern in the southern hemisphere? Australia. It is in the southern hemisphere, yet in the top class, over eighty per cent. Afghanistan is a second anomaly. It sits in the bottom class, under thirty per cent, though its neighbours are higher. One examiner's report on a pattern question with a map notes some students just listed data, which only gave them the mark for using data. The fix is the order. The trend comes first, the figures follow as its evidence, and the anomaly comes last. Every sentence of that answer names places from the map and a class from the key, and none of them gives a reason.

Sometimes the question is about one feature, not a whole pattern. Describing the location of one feature needs two separate pieces of information. One can be a direction and distance from a named place. The other can be a named feature right next to it. Picture a map of part of the fictional land of Owlobia, with a scale bar. A new reservoir sits four kilometres north-east of the town of Hootley. The main road runs just east of the reservoir, and the River Tawny flows two kilometres to its north. The question asks for the reservoir's location, so its size stays out of the answer. Answer A says the reservoir is near the town, below the river. Answer B says it is about four kilometres north-east of Hootley, just west of the main road, with the River Tawny about two kilometres to its north. Which of the two would you write, and why? Answer B. Near and below are not compass directions, and Answer A gives no named place and no distance. One examiner's report on a reservoir question like this says many used words like near, above, below or surrounded by rather than compass directions, and were awarded no marks for it. So give a compass point measured from something named on the map, then add a second, separate fact.

Describe and explain are different jobs. Describe says where something is. Explain says why it is there. Unless a question asks why, a describe answer gives no reasons at all. Picture a dot map of the population of Owlobia, with invented figures, where each dot stands for fifty thousand people. The dots crowd along the River Tawny, which runs from the south of the country to the Barnwing Coast in the north. Near the coast they fan out across the river's delta, the flat, fan-shaped land where a river splits before the sea. A few small clusters sit in the west. Apart from those, the east and the west of the country are empty. Which pattern words fit the dots on that map? Linear, along the River Tawny, and very uneven across the land as a whole. People are almost absent from both sides of the country. Now two answers to a question that asks you to describe it. Answer A says people live by the river because they need its water for farming and drinking. Answer B says the population is very uneven and linear. Most people live in a narrow strip along the river, from the south of the country to the north coast. It goes on: the population is densest in the north, where the dots spread across the delta. Apart from a few small clusters in the west, the east and the west are almost empty. Pick the answer that describes, and say what the other one does instead. Answer B describes. Answer A explains, giving a reason the question never asked for. One examiner's report on a describe-the-distribution question says the vast majority understood what describing a distribution needs. The same report records a minority who went on to outline reasons for the distribution, which was not creditworthy. So stop at where. Keep to describing and you are doing what most students did well, and if a question wants reasons, it will ask why.

Here is the recap, one question at a time, with the answer after each.

What are the three moves of a pattern description, in order? The trend first, then the evidence from the map, then the anomaly.

Now a sentence you have not seen: most farms lie in the east, because the land there is flat. Is that farm sentence a description, an explanation, or both? Both. The first half describes, and the part after because explains, which a describe question does not ask for.

A switch now, to locating one feature. Which locates a school: near the park, or two kilometres west of the station? Two kilometres west of the station, because it gives a compass point and a distance from a named place.

A last one, on a new map. A line of towns runs along a country's east coast, and one large town stands far inland. Which is the anomaly: the coastal towns or the one inland? The one inland, because it breaks the pattern that everything else follows, along the shore.

And the lights of Egypt at night. They form a narrow, linear ribbon along the River Nile, widening in the north across the delta. To the east and the west it is dark desert, apart from a few isolated spots. That is the pattern described, with no reason given.

If you're solid on this, give it a thumbs-up so you know not to watch it twice. If not, save it, because describing a map comes with the questions you practise.

Next in the chapter is GIS: reading layered maps on a screen. Hopefully that's next in your feed, but if not, search for ScholaFly G E oh three, oh three.

Every other video is on scholafly.com too, easy to search by video code or by keyword. Whatever you're revising, go there and have a look, or, watch the next video.