Explain questions: giving reasons how and why

The river through Perchley, a town in the fictional land of Owlobia, has flooded the same street three times in ten years. Who is to blame? All three floods came after a large housing estate was built on the fields upstream. The residents blame the estate, and the builder says it is only heavier rain. Someone may have to pay for flood defences. Pointing at the estate proves nothing on its own, and only a chain of reasons, each link following from the last, can show whether the estate could have done it. That chain is what an explain question asks you to build.

Explain means give the reasons how or why something happens, and each reason is built as a developed point. A developed point has three links. The point says what happens, the because says why or how, and the which means, or the so, says what that leads to. Here is the question for Perchley: explain one way that building a large housing estate can increase the risk of flooding downstream. The point first. The estate replaces fields with roofs, roads and car parks, which are impermeable surfaces, meaning water cannot pass through them. Now the first link. What happens to rain that lands on a roof instead of a field? Because rain cannot soak into those surfaces, it runs straight off into drains and then into the river. Soaking in is called infiltration, and water running over the surface is called runoff. Now the last link: what does all that runoff mean for the river downstream? This means the water reaches the river faster and in greater volume, so the river rises higher and sooner, and it is more likely to burst its banks downstream. That answer has three links for a three-mark question. One examiner's report on a three-mark explain question gives the recipe: "identify a valid factor or reason for the first mark and then make two further explanatory points to gain the additional two marks." Stopping a link early is the slip. Another examiner's report notes: "It was the final double development point that some candidates found more challenging to achieve the 3rd mark." The habit that fixes it is to count your links against the marks before you move on. A different student writes a shorter answer: houses are built, so there is more flooding. Now spot the gap: what is missing from that answer? The middle is missing: the because and the which means. One examiner's report names this: "students simply asserted a connection, leaving the examiner to work out what the link to urban growth or development was in each case." The fix is to write every link, so the reader never has to guess.

Each link in a chain must follow from the one before it, and two examples of the same idea side by side are not a chain. A student's point is: roofs and roads are impermeable. Two students add a second sentence. A: car parks are impermeable too. B: so rain runs off them straight into the drains. Which second sentence develops the point, A or B, and why? B develops it, because it follows on from the point to what happens next. A is a parallel example, another surface of the same kind, so the chain has not moved. One examiner's report on a marked answer says it plainly: "although they have written two ways timber is being used this is only credited as one mark for development." The fix is to ask of each new sentence: does it follow from the last one, or only sit beside it? Precise words carry the chain further, because impermeable, infiltration and runoff each name a step. A bare cause is only the first link, too. One examiner's report on a drought question says: "Other candidates were able to state a cause of drought, but the command word 'explain' meant that linked descriptive ideas were needed to gain credit." The fix is to carry every cause on with so, until it reaches what the question asks about.

An explain two question wants two separate reasons, each developed, and when it gives you a figure, the evidence comes from that figure. A figure shows a national park in Owlobia. The busiest area has a car park for four hundred cars, a railway station and a visitor centre. The quietest area is fifteen kilometres from the nearest road and has no facilities. The question: using the figure, explain two reasons why more people visit some parts of the park than others. Each reason needs evidence from the figure and one developed link. Pause it there and work it out for yourself: two reasons, each with a link. Firstly, access. The busiest area has a railway station and parking for four hundred cars, so visitors can reach it easily by train or car, which means large numbers arrive in a single day. Secondly, facilities. Its visitor centre offers toilets, food and information, so families and older visitors can stay longer. The quiet area is fifteen kilometres from a road with nothing there, so only walkers ready for a long hike reach it. Two separate reasons, each backed by the figure and each developed. Opening them with firstly and secondly lets the examiner find both at once. Now a resource made of figures. In Gradeley, thirty-eight per cent of town-centre shops were empty in twenty twenty-four, up from twelve per cent in twenty fourteen. A retail park with two thousand free parking spaces opened five kilometres away in twenty sixteen. The question asks you to explain why more of the high street now stands vacant, using the figures. The first link is written for you: the retail park opened with free parking, so many shoppers now drive there rather than pay to park in town. Now finish the chain: how do the two percentages become part of the reason? With fewer customers, town-centre shops lose sales and some close, which is why empty shops rose from twelve per cent to thirty-eight per cent between twenty fourteen and twenty twenty-four. Quoting those figures on their own would not explain anything. One examiner's report gives the rule: "One mark only was given to those who cited relevant data without any explanation." The fix is to put each figure inside a reason, as the evidence that the link is real.

Explaining a process means saying why each stage happens, and a list of the stages is only a description. A student writes about a headland: a cave becomes an arch, which collapses to leave a stack. Every stage is there, and not one of them is explained. One examiner's report on a coastal landform question describes answers that "were descriptive, identifying that a cave became an arch and that collapsed to form a stack, with no attempt to explain." What must be added to cave, arch and stack to make that an explanation? The why of each stage. Waves erode a crack in the headland until it widens into a cave. Erosion carries on until the cave breaks through, forming an arch. The roof is worn from below and weathered from above until it collapses, leaving a stack. A case-study question adds one more demand: detail from the place. One examiner's report on the same question says: "The name of the landform is not enough place-specific detail." The habit is to add the rock type, a local figure or a named place to the chain. Explain comes in other shapes too. Some courses print explain one thing and one other thing. On others, give reasons for your answer follows an identify question, and that is an explain question as well. Some explain questions ask for a labelled diagram, which the labelling video covers. One examiner's report on a whole paper describes students showing "increasing confidence in" the explain two questions. Counting links against the marks is how that confidence is built.

Back through the chain one more time, with you doing the linking.

What are the three links of a developed point? The point, then the because, then the which means or the so.

Now a quick one: two examples of the same idea side by side make how many developments? One. A development has to follow from the sentence before it, not sit beside it.

Now a new topic: why might cutting trees on a hillside raise landslide risk? Give the chain. Tree roots no longer hold the soil together, so heavy rain soaks into the slope and loosens it, which means the slope is more likely to slide.

Now the resource row: a figure is quoted with no explanation. What does it need? A place inside a reason, as the evidence that a link in the chain is real.

So who is to blame in Perchley? Roofs and roads stop the rain soaking in, so it runs off fast, which means the river peaks higher and sooner. That chain shows how the estate could raise the flood risk. Whether the heavier rain mattered more is a weighing question, and that is a different command word.

If you own this one, give it a thumbs-up. If the chain is not solid yet, save it, and the rest of the chapter keeps using it, so it comes back round.

Next in the chapter is Suggest questions: reasoned ideas for a situation you have not met. Hopefully that's next in your feed, but if not, search for ScholaFly G E oh one, oh five.

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.