🎧 IELTS Listening – Practice 4
Section 4 · Academic lecture · Questions 31–40. A university lecture on green roofs – where they came from, what they do, why they fail, and where the research is going.
Section 4 has no break – and that changes everything
Sections 1 to 3 stop halfway so you can read ahead. Section 4 does not. The lecture runs from question 31 to question 40 without pausing, so if you stop to think about one answer you will miss the next two. The way through is to decide, before the audio starts, what kind of word each gap needs – and then to keep moving no matter what.
Warm-up A – What kind of word goes in the gap? 6 questions
Warm-up B – Which number do you write? 6 questions
Listening – Section 4 Questions 31–40
💡 Tip: spend the first 45 seconds deciding the word class of all ten gaps. Do not start listening until you have.
Green roofs
Origins
- Turf roofs were normal across northern Europe for hundreds of years
- They were cheap and kept the rain out, but the real purpose was 31
- The modern industry began in Germany in the 1960s
- The driver was not warmth or wildlife but 32
Two types of roof
- Extensive – growing layer no deeper than 33 cm; tough plants that look after themselves
- Intensive – deep soil, supports shrubs and small trees, but the price you pay is regular 34
Benefits
- Surface temperature of the roof falls by as much as 35 degrees
- Across a whole year the roof holds back about 36 per cent of the rain
- The waterproof membrane lasts about twice as long, because it is destroyed by 37
Problems
- The real obstacle to converting an existing building is its 38
- Most early failures happen during the first 39 after planting
Current research
- The most active area is combining plants with 40
| # | Your answer | Correct | Why – and the distractor |
|---|
Spelling counts in the real test. If you heard the right idea but wrote the wrong letters, that is still a lost mark – write the word out three times before you move on.
📜 Lecture transcript (open after you check your answers)
Narrator: Section four. You will hear part of a lecture about green roofs, that is, roofs which are deliberately covered with living plants.
Lecturer: Good morning. Today I want to talk about green roofs, that is, roofs deliberately covered with living plants, and in particular about why cities that had no interest in them twenty years ago are now beginning to make them compulsory.
Lecturer: Let me begin with a misconception. Students often assume that the green roof is a modern invention. It isn't. Turf roofs were standard across northern Europe for centuries, and although they were certainly cheap, and although they did keep the rain out ← two traps, both rejected, neither of those was the point of them. The point was insulation. A thick layer of soil and grass kept the heat inside the building through the winter, and that is why they survived for so long in cold climates. ← Q31 = insulation
Lecturer: What changed in the twentieth century was the motive. The modern industry began in Germany in the nineteen sixties, and the driver was not warmth, and it was not, at that stage, wildlife ← traps. It was flooding. German cities had paved over so much ground that the drains could no longer cope with heavy rain, and engineers realised that a roof full of soil behaves like a sponge. ← Q32 = flooding
Lecturer: Now, the distinction you must not blur is the one between extensive roofs and intensive roofs. An extensive roof carries a shallow layer of growing material, normally no more than fifteen centimetres deep, and it is planted with low, tough species that look after themselves. ← Q33 = 15 An intensive roof is quite different. The soil is much deeper, half a metre is common ← trap: that is the OTHER type, so it can support shrubs and even small trees. But the price you pay for that is maintenance. Somebody has to go up there and cut it, feed it and water it, and if nobody does, an intensive roof fails within a couple of seasons. ← Q34 = maintenance
Lecturer: So what do they actually do? The first benefit is temperature. On a hot afternoon a conventional black roof can reach seventy degrees ← trap number. Put plants on it and the surface temperature falls by as much as thirty degrees. That is not a small correction. It is the difference between a building that needs air conditioning all afternoon and one that does not. ← Q35 = 30
Lecturer: The second benefit takes us straight back to Germany. A green roof does not stop the rain, but it delays it. Measurements vary a good deal with the season, and in a single summer storm the figure can be as high as eighty per cent ← trap number. But averaged across a whole year, a typical extensive roof holds back about fifty per cent of the rain that falls on it, and fifty is the figure you should quote in an essay. ← Q36 = 50
Lecturer: The third benefit is the one building owners care about most, and it is the least obvious. Underneath the soil there is a waterproof membrane, and what destroys that membrane is not water, and it is not frost ← traps. It is sunlight. Ultraviolet light makes it brittle, and it cracks. Bury it under soil and plants and you can roughly double its working life. ← Q37 = sunlight
Lecturer: Now the problems, because there are several. Cost is the one that gets quoted in the newspapers, but cost is a solvable problem ← trap. The real obstacle, the thing that stops most conversion projects before a single plant is bought, is weight. Saturated soil is extremely heavy, and most existing buildings were simply never designed to carry it. ← Q38 = weight
Lecturer: The second problem is that a great many green roofs fail early, and the failures cluster in a very predictable place. It is not the first winter, which is what most people expect ← trap. It is the first summer. The plants have not yet rooted deeply, the layer of soil is thin, and if nobody waters them through a dry August, they simply die. ← Q39 = summer
Lecturer: Finally, where is the research going? There is work on lightweight growing materials, and there is a good deal of interest in food production on city rooftops ← two traps. But the most active area at the moment, and the one I would recommend for your own project, is the combination of plants and solar panels. It turns out that a panel sitting above a cool, damp green roof generates measurably more electricity than exactly the same panel on a hot bitumen surface. ← Q40 = solar panels
Narrator: That is the end of section four. You now have half a minute to check your answers.
What to do next
Scored 8 or more? You are ready for the full timed test, where Section 4 arrives after twenty-five minutes of concentration and feels twice as fast. Scored 5 or fewer? Do not replay the whole lecture. Open the transcript, find the three gaps you missed, and read only the sentence before each one – the answer is almost always introduced by a signal such as the point was, the real obstacle is, the figure you should quote.