Mistakes That Can Cost You Your EBAU Score (and How to Avoid Them)

The difference between a 6 and an 8 on the EBAU isn't always about knowing more. Often, it's about making fewer avoidable mistakes. Mistakes that have nothing to do with what you know, but with how you manage the exam, your time, and your strategy.

Every year, thousands of students lose points not from lack of knowledge, but from execution errors that can be prevented with practice.

This article covers the most frequent mistakes we see in selectividad, sorted by type. If you identify them before the exam, you can train yourself to avoid them.

Time Management Mistakes

These are the most painful because they don't depend on what you know. You can master the syllabus and still lose points from poor time management.

Not Calculating Time Per Question Before Starting

The most basic and widespread mistake. The exam begins and you jump straight into answering the first question without planning how much time to spend on each one.

What happens: you spend 40 minutes on a 2-point question and then have 20 minutes left for a 3-point one. Your score doesn't reflect what you know, but how poorly you distributed your time.

How to avoid it: before writing anything, spend 2 minutes reading all questions and assigning time proportional to their weight. If a question is worth 3 out of 10 points, it deserves 30% of the available time. Write the time limit for each question in the margin.

Getting Stuck on a Difficult Question

It's tempting to keep trying to solve the question you can't figure out. But every extra minute you invest in it is a minute stolen from questions you could answer well.

What happens: your brain enters tunnel mode. You feel that abandoning the question means accepting defeat. When you finally check the clock, you've lost 15 minutes you needed elsewhere.

How to avoid it: set a rule before the exam: if in 5 minutes you haven't made significant progress on a question, mark it, move on, and come back at the end if there's time. Practising this in mock exams makes it automatic.

Not Leaving Time for Review

Reviewing in the last 5-10 minutes isn't a luxury. It's where you catch calculation errors in Maths, spelling mistakes in Language, confused dates in History, or unit errors in Physics.

What happens: the exam ends and you haven't reviewed anything. You submit with errors you would have caught in 3 minutes of re-reading.

How to avoid it: when planning your time at the start, always reserve 5-10 minutes at the end. If you have more time left, even better. If you don't review, those points are lost to carelessness, not ignorance.

Subject-Specific Mistakes

Each subject has its own traps. Knowing them is half the battle.

Spanish Language and Literature

Not structuring the text commentary. The most expensive mistake in Language. Writing a disorganised commentary, jumping from idea to idea without clear structure. Examiners value organisation as much as content.

Solution: always use a fixed outline: introduction (text type, theme, context), content analysis (structure, main ideas), form analysis (stylistic devices, register), personal assessment (argued, not just opinion). Practise this outline until it's automatic.

Confusing types of stylistic devices. Calling a simile a metaphor, or labelling a repetition as anaphora when it isn't. Seems minor, but it shows lack of terminological precision and costs points.

Forgetting accents and spelling. In a Language exam, spelling errors penalise more than in any other subject. Some examination boards deduct up to 0.5 points for repeated mistakes.

History of Spain

Mixing up chronology. Placing the 1876 Constitution before the First Republic, or confusing the order of Transition governments. In History, a chronological error invalidates the argument.

Solution: before starting to write a development answer, make a quick timeline on scratch paper with the 5-6 key dates for the topic. It takes 2 minutes and prevents confusion.

Unstructured development. Writing everything you know about the topic in random order. A History development needs: context (what was happening before), chronological development of the topic, consequences, and if appropriate, a conclusion. Without structure, it looks like you're dumping notes, not answering a question.

Not answering what's being asked. If the question is about "The Second Republic: reforms and conflicts", don't write the entire history of 20th century Spain. Focus on the specific period. Examiners penalise irrelevant filler.

Mathematics

Not showing intermediate steps. Writing only the final result without showing your work. If the result is wrong but the approach was correct, you lose all points. If you show your steps, you can get partial credit.

Solution: write every step, even if it seems obvious. Justify intermediate steps. Examiners can't give you points for what they can't see.

Sign errors and basic arithmetic mistakes. The classic. You know how to differentiate perfectly but make a sign error at the beginning and carry it through to the end. A -1 that should be +1 can cost you the entire question.

Solution: when you finish a problem, go back and verify the basic operations. Errors are almost always in the simple parts, not the complex ones.

Not checking whether the result makes sense. If you calculate that the probability of an event is 1.3, something's wrong. If the distance between two points comes out negative, something's wrong. Many errors are caught with a quick coherence check.

Forgetting units. In Physics or Applied Maths problems, a result without units or with incorrect units loses points. Units aren't decoration — they're part of the answer.

To memorise formulas and key data without forgetting them on exam day, flashcards with spaced repetition are the most scientifically backed method.

English

Not respecting the word limit in writing. If they ask for 150-180 words, don't write 250. You won't get more points for writing more; on the contrary, they may penalise lack of conciseness.

Using risky vocabulary you don't command. It's tempting to use sophisticated words to impress, but if you use them incorrectly, the effect is the opposite. A correct sentence with simple vocabulary is better than an incorrect one with complex vocabulary.

Not re-reading the text in reading comprehension. Many incorrect answers come from answering from memory after a quick first read, without going back to the text to verify. If the answer is in the text, go back and read it. Don't trust your memory.

Ignoring connectors. A writing piece without connectors (however, moreover, in addition, on the other hand) looks like a list of disconnected sentences. Connectors don't just improve your coherence score — they also help you organise your ideas.

Elective Subjects (Physics, Chemistry, Biology, Economics...)

In Physics/Chemistry: not writing the formula before substituting. Write the general formula first, then substitute the values. If you substitute directly and make a mistake, the examiner can't give partial credit because they don't know which formula you were trying to apply.

In Biology: being too vague. "The cell divides" is not an acceptable answer in selectividad. You need terminological precision: mitosis, meiosis, specific phases, structure names. The difference between passing and scoring well lies in the terminology.

In Economics: not using data or examples. Theoretical answers without practical application fall short. If you explain the law of supply and demand, include a concrete example. Examiners value the ability to apply, not just recite.

Strategy Mistakes

These mistakes are made before the exam, but their consequences show up on the day.

Choosing the Wrong Voluntary Phase Subjects

The mistake: choosing voluntary subjects based on ease rather than weighting. You score a 9 in a subject that weights 0.1 for your degree (adding 0.9 points) when you could have scored a 7 in one that weights 0.2 (adding 1.4 points).

How to avoid it: before deciding, check the weighting tables for the universities you're interested in. Do the maths. Sometimes the "harder" subject is the best strategic choice.

Not Doing Mock Exams Under Real Conditions

Studying a lot but not practising the exam format is like training for a marathon by only running sprints. The knowledge is there, but the execution fails.

What happens: on exam day you encounter a format you know in theory but have never practised with a timer, without notes, and under real pressure. Performance drops 15-20% from what you could have achieved.

How to avoid it: at least once a week in the two months before the exam, do a full mock of one subject under exam conditions. ExamFlow lets you generate exams tailored to your material so you never run out of practice material.

Only Studying What You Enjoy

It's human. You spend more time on subjects you're good at because it's more pleasant. But the final score is the average of everything, and a 4 in one subject drags you down more than a 9 in another compensates.

How to avoid it: plan study time inversely proportional to your level. If you already score 8 in English but 5 in Maths, Maths needs twice as many hours as English. Not the most fun approach, but the most efficient. The Pomodoro method combined with active recall helps you stay focused on the subjects that motivate you least.

Not Knowing the Marking Criteria

Each autonomous community publishes the marking criteria from previous years. Many students never read them.

What happens: you answer correctly but not in the way the examiner expects. In History, structure might be valued more than the amount of data. In Maths, the approach might be worth more than the result. If you don't know the criteria, you're playing blind.

How to avoid it: look up the marking criteria for your autonomous community from the last 2-3 years. Read them before doing mock exams. Adapt your answering style to what's expected.

Exam Day Mistakes

Not Having Breakfast (or Having a Bad One)

Your brain consumes 20% of your body's energy. A 90-minute selectividad exam requires maximum concentration. If you arrive on an empty stomach or having only had coffee, your cognitive performance drops after 45 minutes.

Ideal breakfast: something with complex carbohydrates (wholemeal bread, oats), protein (eggs, ham) and fruit. Avoid excess sugar, which causes a spike and crash.

Not Bringing Spare Materials

A pen that runs out of ink mid-exam. A calculator with dead batteries. Seems unlikely, but it happens every year.

Always bring: two pens, a pencil, eraser, calculator with fresh batteries (if allowed), ID, water, and something to eat between exams.

Arriving Just in Time

The stress of arriving late or just on time affects your performance for the first 15-20 minutes. Your body is in alert mode, not concentration mode.

Arrive 20-30 minutes early. That gives you time to sit down, breathe, organise your materials and read the exam calmly.

Pre-EBAU Checklist

Use this checklist in the weeks before the exam:

• I've done at least 5 complete mock exams under real conditions
• I know the marking criteria for my autonomous community
• I've calculated the optimal weighting for the voluntary phase
• I have a time plan for each type of exam
• I've practised the review technique in the last 5-10 minutes
• I know what to do if I go blank on a question
• I have my materials ready (pens, calculator, ID)
• I know the exact location of the exam centre
• I've practised 4-7-8 breathing for managing nerves

Conclusion

Most of these mistakes have something in common: they're avoided through deliberate practice, not more study hours. Doing mock exams under real conditions, knowing the marking criteria, and having a time management plan gives you a real advantage over someone who only studied the syllabus.

If you want to practise with exams generated from your own material, with automatic grading and detailed feedback, try ExamFlow free for 14 days. Generating practice exams is the most direct way to catch these mistakes before they count.

And if you want a complete month-by-month planning guide, check out our study guide for selectividad 2026.