The shape of the question
A rhetorical synthesis item gives you three things, in this order on the screen and in this order of importance to you:
- Notes — four to six bullet points a student has taken while researching.
- A goal — one sentence beginning The student wants to…
- Four sentences, each of which could plausibly appear in the student's write-up.
Every one of the four sentences is normally true according to the notes. Accuracy is not the test. The test is whether the sentence does the job the goal describes.
Order of operations. Goal first. Then split the goal into its two criteria and mark them. Then read the notes with those two criteria already in mind. Then the choices. Reading the notes first means reading six facts with no idea which two matter.
Học sinh gần như luôn đọc từ trên xuống: ghi chú trước, mục tiêu sau. Đó là lý do dạng này ăn nhiều thời gian nhất trong cả phần Đọc–Viết. Sáu gạch đầu dòng đọc mà không biết mình đang tìm gì thì phải đọc lại lần hai. Kéo mắt xuống câu The student wants to… trước, đọc kỹ đúng một câu đó, rồi mới quay lên. Một lần đọc ghi chú là đủ.
Split the goal into two criteria
A goal sentence is almost never a single instruction. It is two, joined so smoothly that they read as one.
The student wants to emphasise a similarity between the two dating
methods.
Criterion 1 — the rhetorical move: emphasise a similarity (not a difference, not a
description).
Criterion 2 — the scope: both methods must appear. A sentence about one of them cannot
state a similarity between two.
A choice must satisfy both. Satisfying one is what every good distractor does.
Notes:
- Radiocarbon dating measures the decay of carbon-14 and needs organic material.
- Its useful range runs from about 300 to about 50,000 years.
- Potassium–argon dating measures the decay of potassium-40 in volcanic rock.
- Its useful range runs from about 100,000 years to billions of years.
- Both methods depend on the fixed decay rate of an unstable isotope.
- Neither method dates an artefact directly; each dates material found with it.
- Radiocarbon dating is useful from about 300 to about 50,000 years, while potassium–argon dating begins at roughly 100,000 years.
- Radiocarbon dating requires organic material, which is why it cannot be used on the volcanic rock that potassium–argon dating needs.
- Both methods have been refined since the 1950s and are now accurate enough for most archaeological purposes.
- Both radiocarbon and potassium–argon dating work by measuring the decay of an unstable isotope at a rate that does not change.
Criterion 1: a similarity. Criterion 2: both methods. (A) covers both methods but states a difference — criterion 1 fails. (B) covers both methods and again states a difference, dressed up as an explanation. (C) does claim something of both methods, but “refined since the 1950s” and “accurate enough” appear nowhere in the notes. (D) names both and states the property they share. Answer (D).
Same notes as above.
- Radiocarbon dating reaches back about 50,000 years, whereas potassium–argon dating cannot be used on anything younger than roughly 100,000.
- Both radiocarbon and potassium–argon dating rely on the decay of an unstable isotope proceeding at a fixed rate.
- Radiocarbon dating measures the decay of carbon-14, an isotope that is produced in the upper atmosphere and taken up by living tissue.
- Neither radiocarbon nor potassium–argon dating puts a date on the artefact itself; both date the material found alongside it.
The notes have not changed and neither have the facts; only the goal has. Now (B) and (D) fail, because both state similarities. (C) describes one method only, so the scope criterion fails — and “produced in the upper atmosphere” is not in the notes either. (A) names both and sets their ranges against each other. Answer (A).
Hai ví dụ trên dùng đúng một bộ ghi chú và đúng bốn loại phương án — chỉ đổi câu mục tiêu, đáp án đổi theo. Đây là toàn bộ tinh thần của dạng bài: bốn câu kia không sai sự thật, chúng chỉ làm sai việc. Vì thế đừng bao giờ chấm phương án bằng câu hỏi “câu này có đúng không”, mà bằng câu hỏi “câu này có làm đúng việc mục tiêu yêu cầu không”.
The three ways a choice fails
- Half the goal. True, drawn from the notes, but it meets one criterion and not the other — a difference where a similarity was asked for, or one item where two were required.
- Imported information. It meets both criteria but leans on a fact that is not in the notes. Anything you know from outside is not evidence here.
- Wrong emphasis. Everything in it is in the notes and both criteria are technically met, but the sentence buries the required point in a subordinate clause and foregrounds something else.
Kiểu nhiễu số 2 là kiểu ăn điểm học sinh giỏi. Câu đó đọc lên hay nhất, mượt nhất, “nghe giống văn học thuật” nhất — vì người ra đề thêm vào một chi tiết nghe rất hợp lý mà ghi chú không hề có. Quy tắc cứng: mọi mệnh đề trong phương án phải truy được về một gạch đầu dòng. Không truy được là loại, dù nó đúng ngoài đời thật.
Notes:
- Glass sponges build skeletons out of silica.
- Reefs made by glass sponges were known only from Jurassic rock and were assumed to have disappeared about 40 million years ago.
- In 1987 a survey found living glass sponge reefs on the shelf off British Columbia.
- The reefs stand up to nineteen metres above the seabed.
- A single sponge can filter thousands of litres of water a day.
- Canada declared the largest reefs a marine protected area in 2017.
- The reefs, which stand up to nineteen metres above the seabed, were declared a marine protected area by Canada in 2017.
- Because a single sponge filters thousands of litres a day, the reefs play a disproportionate role in cleaning the water column.
- Glass sponge reefs are undersea structures built by sponges with silica skeletons, and living examples were found off British Columbia in 1987 after being known only from Jurassic rock.
- Glass sponge reefs, a Jurassic survivor that scientists had long hoped to rediscover, finally turned up in Canadian waters.
“An audience unfamiliar with them” is itself a criterion: the sentence has to say what the thing is before saying anything else about it. (A) and (B) both assume the reader already knows. (D) says what the thing is only vaguely and imports “scientists had long hoped to rediscover”, which no note supports. (C) defines the object and then places it. Answer (C).
Emphasis is part of the goal, not decoration
When a goal says emphasise, the required point has to be in the driving position of the sentence — the main clause, not a relative clause hung off the end. Two choices can contain the same facts and only one of them can emphasise the right one.
Notes:
- Hedy Lamarr and the composer George Antheil patented a “Secret Communication System” in 1942.
- The system switched a radio signal across 88 frequencies in a set order.
- The two ends were kept in step by perforated paper rolls of the kind used in player pianos.
- Its stated purpose was to stop a torpedo's guidance signal from being jammed.
- The US Navy did not use the system during the Second World War.
- Frequency hopping entered military use in the 1960s, after the patent had expired.
- Lamarr and Antheil's system, patented in 1942, kept its two ends synchronised with perforated paper rolls borrowed from the player piano.
- The system was designed to keep a torpedo's guidance signal from being jammed by hopping it across 88 frequencies in a set order.
- Although the patent was granted in 1942, frequency hopping did not enter military use until the 1960s, by which time it had expired.
- Frequency hopping, now familiar from Bluetooth and Wi-Fi, began as a wartime idea that the Navy chose to ignore.
The goal names one thing: purpose. (A) describes the mechanism, (C) describes the delay, and both are accurate and both are off-task. (D) imports Bluetooth and Wi-Fi, which the notes do not mention. (B) puts the purpose in the main clause and uses the mechanism only to support it. Answer (B).
Same notes as above.
- Lamarr and Antheil's system hopped a radio signal across 88 frequencies, synchronised at both ends by paper rolls of the kind used in player pianos.
- The Navy's decision not to use the system in the Second World War was one of many missed opportunities in wartime procurement.
- Frequency hopping was patented in 1942, and the principle is still in use today.
- Patented in 1942 to protect torpedo guidance from jamming, the system was passed over by the Navy and only entered military use in the 1960s, after the patent had run out.
Two criteria: a gap, and both of its ends. (A) gives neither end. (B) gives one end and then imports a claim about wartime procurement in general. (C) names 1942 and “today” but “still in use today” is not in the notes, and the sentence does not present the delay as a gap at all. (D) dates both ends and makes the delay the point of the sentence. Answer (D).
Chú ý mấy động từ trong câu mục tiêu, chúng không đồng nghĩa: emphasise (đưa ý đó lên mệnh đề chính), introduce (phải nói cái đó là gì trước), explain (phải có nguyên nhân hoặc cơ chế), present the conclusion (phải là kết luận chứ không phải dữ liệu thô), specify (phải có con số hoặc tên riêng), compare (phải có hai vế đặt cạnh nhau trong cùng một câu).
Numbers in the goal, numbers in the answer
When the goal asks for a comparison of two quantities, the correct choice states both quantities in the same sentence and in comparable terms. A sentence that quotes one number and characterises the other in words is not a comparison.
Notes:
- Silica aerogel is roughly 99% air by volume.
- Its thermal conductivity is lower than that of still air.
- It is brittle and cracks under a point load.
- NASA used aerogel to catch comet dust on the Stardust mission.
- Aerogel costs far more per cubic metre than foam insulation.
- A slab thin enough to be handled can hold back the flame of a blowtorch.
- Aerogel is about 99% air by volume, and it conducts heat even less readily than the still air it mostly consists of.
- Aerogel is a remarkable material with many applications, including one on a NASA mission to sample comet dust.
- Aerogel is brittle, so a slab of it will crack if the load is concentrated at a single point.
- Aerogel is expensive, but its insulating power per centimetre of thickness has made it standard in spacecraft and in high-end outdoor clothing.
“Specify” rules out (B), which specifies nothing. (C) is a fact from the notes but not about insulation. (D) imports “standard in spacecraft and in high-end outdoor clothing”. (A) gives the figure and the property that makes it surprising. Answer (A).
Phương án chứa con số không tự nhiên đúng. Rất nhiều nhiễu được viết bằng cách lấy đúng một con số trong ghi chú rồi gắn vào một mệnh đề trả lời sai câu hỏi. Con số chỉ có giá trị khi nó phục vụ đúng tiêu chí — “specify”, “compare”, “quantify”. Mục tiêu không đòi con số thì con số là mồi.