Imagine: you're sitting the TSA exam, 10 minutes left in the section, and you're faced with a problem about bus routes where you need to choose the most efficient schedule. You've read the question three times, but you're still not sure which data are important and which are noise. Sound familiar? It's precisely on such problems that most applicants lose precious marks, even though their maths and logic are fine. The TSA isn't about knowing facts; it's about thinking quickly and accurately under uncertainty. And preparation breaks down not on hard questions but on simple ones where everything seems obvious.
What the TSA is and why it's harder than it looks
The TSA (Thinking Skills Assessment) is an admissions test used by Oxford, Cambridge and UCL to select candidates for a range of courses. It consists of two sections: Problem Solving and Critical Thinking. The first tests the ability to analyse quantitative information, spot patterns and algorithms. The second tests the ability to draw logical conclusions, recognise assumptions and errors in reasoning. For Oxford there is additionally an essay (30 minutes, one topic out of four).
At first glance, what's so hard? It's not physics or advanced maths. But the catch is that the TSA doesn't test your store of knowledge; it tests mental flexibility. The problems are designed to confuse: they contain lots of redundant data, non-obvious wording, and time is strictly limited. For example, in the Problem Solving section you get 25 questions in 40 minutes — essentially a minute and a half per question. In that time you need to read the question, discard the irrelevant, build a model and choose an answer. Many applicants with high academic grades fail precisely because they can't work at that pace.
What's the deeper difficulty? The TSA requires switching between different types of thinking. One moment you're solving a ratio problem, the next you're analysing an argument for a logical flaw. The brain resists such context switching, especially under time pressure. And here it's important not just to drill typical problems but to understand the mechanics of each type of reasoning.
Breaking down one problem: how a practitioner solves Problem Solving
Let's take a typical TSA problem (adapted for the example). The question: "A company transports goods. On the first day it transported 120 tonnes, which was 15% of the total order. On the second day — 40% of the remaining goods. How many tonnes are left to transport?"
How does a novice reason? They see percentages and immediately try to calculate 40% of 120 tonnes — getting 48 tonnes, subtracting from 120 — getting 72 tonnes. And they're wrong. Because the 40% is taken not from 120 but from the remaining goods. This is a classic trap for attentiveness.
How does a practitioner act? They break the problem into steps and explicitly state what is calculated from what.
Step 1. Find the total weight of the order. If 120 tonnes is 15%, then 1% = 120 / 15 = 8 tonnes. Then 100% = 8 × 100 = 800 tonnes.
Step 2. Calculate the remainder after the first day: 800 – 120 = 680 tonnes.
Step 3. Find how much was transported on the second day: 40% of 680 = 0.4 × 680 = 272 tonnes.
Step 4. Remainder: 680 – 272 = 408 tonnes.
Answer: 408 tonnes. The key difference is that at each step the practitioner checks which base the percentage refers to. This takes an extra 10 seconds but saves you from error.
What would go wrong if done otherwise? If you calculate 40% of 120, you get 48, remainder 72 — and that's fundamentally wrong. In the TSA such traps occur constantly: percentages of percentages, changing base, relative and absolute quantities. The practitioner always asks: "What is this percentage calculated from?" — and only then calculates.
Another nuance: in the TSA you often need to choose the most efficient algorithm. For example, several schedule options are given, and you need to find the one that minimises total time. Here it's important not just to calculate each option but to discard obviously suboptimal ones using logical reasoning. This saves time.
Critical Thinking: where logic breaks down
The Critical Thinking section seems easier because there are no calculations. But this is exactly where applicants lose the most marks. The problems are based on analysing short texts: you need to identify the main conclusion, find the assumption, evaluate the strength of an argument, detect a logical flaw.
Consider an example. Text: "All students who do well in exams attend extra classes. Ivan attends extra classes. Therefore, Ivan does well in exams." Question: what assumption underlies this reasoning?
Many answer: "Ivan is a student." But that's not an assumption, it's a condition. The real assumption is that attending extra classes is a sufficient condition for doing well. That is, that everyone who attends classes does well. The original only says that all who do well attend classes (a necessary condition), but the conclusion is drawn as if from a sufficient one. This is a classic error — affirming the consequent.
A practitioner spots such constructions immediately because they are trained to identify the structure of an argument. They don't read the text as a story but break it down into premises and conclusion, checking whether the conclusion follows logically. In the TSA this is a key skill.
Another type of problem is evaluating additional information. An argument is given, and you're asked which of the additional statements would weaken or strengthen it. Here it's important to understand what "weaken" means: it doesn't mean "refute" but "make less convincing". Many confuse these concepts and choose the wrong answer.
The Critical Thinking section also includes problems on applying principles. For example, a principle is given: "If an action causes harm to others, it is morally unacceptable." And you need to determine which of the actions violates this principle. Here it's important to clearly define what counts as harm and what doesn't. Usually such problems include borderline cases, and you need to choose the most obvious one.
Where the TSA preparation mechanism itself breaks down
Even motivated applicants can have their preparation go wrong. Here are several scenarios where the scheme fails.
Scenario 1: change in test format. The TSA changes periodically: sometimes new types of problems are added, sometimes the essay is removed. If you prepare using old materials, you may train on problems that no longer exist. How to notice in advance? Follow official updates on university websites. If it's already too late — switch to current practice tests, even if they seem harder.
Scenario 2: the rule doesn't apply. You've learned that in a percentage problem you must always find the base. But then you encounter a problem where percentages are already given from different bases, and you simply need to compare proportions. Your template doesn't work. How to notice? If the solution takes too long or leads to an absurd answer, you're applying the wrong template. The way out is to return to the question and rephrase it in your own words.
Scenario 3: time's up. In the exam you get stuck on one problem and lose 5 minutes. In the TSA that's a disaster: you won't have time to solve the rest. How to notice in advance? In practice, time each problem. If a problem takes more than two minutes, skip it and come back later. If it's already too late — guess the answer and move on, otherwise you'll lose more.
Scenario 4: the tool stops working. You're used to solving problems on rough paper, but in the exam there may be no rough paper or very little. Or you're used to using a calculator, but it's banned in the TSA. How to notice? Check the exam rules in advance. If it's already too late — practise mental arithmetic and making notes in the booklet itself (if allowed).
Ways to master it: self-study vs a structured course
When you understand that the TSA is a skill, not a set of facts, the question arises: how to train it? There are several paths, and each has its trade-offs.
Self-study. You find practice tests online, solve them, check answers. Pros: free, flexible schedule. Cons: no feedback during the solution process, you don't know why you made a mistake, and you don't see how an expert reasons. As a result, you may learn the wrong algorithm and waste time. Moreover, self-study requires high self-discipline and the ability to find quality materials.
Courses and tutors. Here you get structure and feedback. But quality varies greatly. A good course doesn't just give problems but analyses the mechanics of the solution: why this answer is correct and that one isn't, what traps are built in. However, courses cost money, and not everyone can afford them.
Practice with a mentor. One-to-one sessions with someone who has already scored high on the TSA is the most effective but also the most expensive path. You get personalised recommendations and error analysis. But finding such a mentor is difficult, and the cost may be high.
What to choose? If you have time and discipline, you can start with self-study, but be sure to check your reasoning against detailed explanations. If you feel stuck or lack feedback, consider a structured course. For example, Cambridge Admissions: TSA (Thinking Skills Assessment) offers personalised lessons tailored to the student's level, where exactly such problems as in the example above are analysed, with a focus on the mechanics of solving. This isn't the only option, but it removes the barrier of lacking feedback.
Also keep in mind that TSA preparation may overlap with preparation for other admissions tests, such as the BMAT or Cambridge Admissions. Critical thinking skills are useful everywhere.
Who the TSA path suits and who it doesn't
The TSA is a selection tool for those applying to certain courses at Oxford, Cambridge and UCL. If you're not planning to apply there, you don't need the TSA. But if you are, it's worth understanding whether this format suits you.
Who it suits: those who can make decisions quickly, don't get flustered when the context changes, enjoy logical problems and are ready to train their thinking rather than rote-learn. It also suits those ready to invest in preparation systematically, because the TSA requires building automaticity.
Who it doesn't suit: those who prefer deep immersion in one topic rather than quick switching; those who work poorly under time pressure; those who expect that learning formulas is enough. The TSA isn't about that.
If you've realised that the TSA is your challenge and you want to prepare in a structured way, take a look at the course Cambridge Admissions: TSA (Thinking Skills Assessment). It analyses exactly the mechanics discussed: how to identify relevant data, how to build conclusions and avoid logical errors. Details and enrolment are on the course page. See also , and Go for Backend (gRPC).