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Error detection tasks: the nightmare of many ESL (English as a second language) learners. Many of my most advanced students described this task type as the trickiest little beast of all in the Use of English part of the advanced level matura exam.

Not only do they feel like you might be feeling right now: clueless and like it is a shot in the dark, blindly guessing what word could be the odd one out, but there is also little help online in this, and teachers often just shrug it off saying “yeah, this is not good there because it doesn’t fit in the sentence”. Of course, as with all érettségi tasks, practice makes perfect; and after doing 10-20 sets of these tasks (you can find them all listed out here), you will be able to make intelligent guesses and start to develop an intuitive sense about what could be wrong and what to be looking out for.

Still, let me maybe help you organize your thoughts and elaborate on your gut feelings, so you can make sure to pass this task with flying colours. Remember, this is the only task type that will be there each year, no matter if you like it or not.

And if you are a teacher, this post will give you some actionable insights on how you can help your students in error detection tasks, backed up by a little bit of research and statistics.

Error detection tasks and spot-the-difference puzzles

Before we dive deeper into error detection tasks, let’s describe the general idea of this task type: you have to decide if the line contains an error or not, where the error can only be an unnecessary or redundant word, nothing else.

As misleading it might be, this type is also sometimes referred to as “error correction” (hibajavítás); however, we always have to bear in mind that error detection tasks in the érettségi do not involve correcting mistakes – you just have to spot one single word that does not fit in the sentence in each line (if there is any).

As a kid, you must have played Where’s Waldo? and spot-the-difference kind of puzzles, and we may as well call up those memories to understand more about the nature of error detection tasks. Practically, they are all spot-the-difference puzzles with the text, a string of correct and incorrect sentences in front of you and proper English grammar in your head. As you slowly got the hang of what to look for when comparing two versions of the same picture (the number of tree branches, the clock face in the background, the color of the girl’s jumper etc.), you can also learn the most frequent grammar mistakes that the creators of error detection tasks hide in the text and why they specifically choose those typical errors.

Sticking with this analogy, I will now define three levels of these errors: cat-and-dog (easy), cat-and-another-cat (moderate), and twin-cats (difficult) kind of errors in these tasks. Apart from similarity, these colliding grammar structures can also be presented as two points on a scale from correct to incorrect, meaning that we can also describe them using more of a boring language: correct-and-incorrect (cat-and-dog), correct-and-less-correct (cat-and-another-cat), and correct-and-correct (twin-cats) structures.

Cat-and-dog errors: the easy kind

This is practically the equivalent of finding a single difference between the picture of a cat and a dog: very obviously, one of them is a cat and the other one is not. In terms of error detection tasks, this means that the structure you are considering is ungrammatical in the most obvious way, and no similar kind exists in the English language.

Given that this is the advanced level érettségi hitting the same level as a B2 language exam, you will not be able to find many examples of this type, but you might come across these ones sometimes. They break basic grammar rules and you do not really have to deal with much of the meaning of the sentence or the broader environment of the word because they are inherently wrong.

Consider the following set of examples for size:

October 2019, Item 32

By the time you reach the end of the sentence, you might already feel some kind of hesitation, something is wrong, something is missing. As their Hungarian name implies (névelő), articles can only be followed by a noun phrase; you might as well just ask: “A responsible what?” Without the noun after the adjective responsible, this structure will not work in a million years, especially if it is followed by the word for, the complement of responsible, which makes it even harder to use any noun there anyways.

Another case for a similar error is abstract nouns (love, happiness, time), which will almost never take an article (eg. All You Need Is Love by The Beatles). As they are short little words and relatively easy to miss, examiners often put extra articles in the lines (amounting to 7% of all errors in the last 20 years), so if you see one of them, think twice.

October 2015, Item 33

If you know me, you also know my golden rule: an English sentence always has one single finite verb (ragozott ige). Did is the past simple (or second) form of do as is hoped of hope. Either one, or the other, you can’t have it both ways. Which one should you keep? The one that you can use to introduce a subordinated clause (ie. there was an interest), or another sentence, broadly speaking. With did, you can’t do that, with hoped you can.

(Mind you, this is a borderline cat-and-another-cat type as you can use do and did in an emphatic way [he did hope meaning ‘he really hoped’]; however, you can’t use anything else than the base form of the verb [hope] after that.

October 2015, Items 37-38

Are you feeling strange when reading the above line? Read it again, stopping after features, and you will easily tell why: your mind automatically interprets the word features as a plural noun, and if you continue, only further nouns follow without any kind of connector (and, or, with etc.). Even though you can put two nouns together in English (that’s how you get compound nouns like coffee table or bus stop), you can’t really do that with plural nouns (with rare exceptions like sales figures or customs regulations), especially not with a number in the middle.

October 2012, Item 38

Superlatives are lonely guys: they don’t ever meet another one of their kind, and even if they do, at least a comma always stands between them. However sad their life could be, this makes your life very easy in this case: it is either a short adjective and you can put -est at the end of it, or a longer one where you have to use most. One or the other.

May 2007, Item 29

The other golden rule of English sentences: there is always a finite verb in their heart. They talking might be used in colloquial English, but it is not correct here, or anywhere else for that matter unless it is is in a language exam. They talk, or they are talking, but we can’t get rid of -ing as this is not an error correction task; if it’s one single word that could be removed, it is they, resulting in the use of the advanced structure when/while + V-ing.

The cat-and-another-cat type

Next up, we have the moderate kind of errors, easy to spot the line with these errors, but it is a bit harder to decide which word we can go without. The reason for this difficulty is that both structures do indeed exist in English.

For example, the tenses (and the structure would + V) below are made up of an auxiliary (segédige) and a main verb, so teachers can use them in error detection tasks to try and see if examinees really know when to use which. In other words, similar structures can be matched with their single-part counterparts as follows:

1. Present Perfect (have/has tricked) and Past Simple (tricked)

2. Past Perfect (had tricked) and Past Simple (tricked)

3. Future Simple (will trick) and Present Simple (trick)

4. Modal verbs (can, would, could, should trick) and Present Simple (trick)

5. Passive voice (was tricked) and active voice (tricked)

This type occurs very often too (17% of all errors), so you better take special care when coming across an auxiliary of any kind, and if you’d like to ace this task, you’d better double-check your tenses, modalities, and voices (active and passive, respectively).

Let’s see some of these auxiliaries in action.

October 2017, Item 25

October 2016, Item 24

May 2012, Item 37

As you might already see, certain shades of added meaning make these auxiliaries unnecessary here: the first example has nothing to do with the present (this is classic story-telling which should all be in past tenses), while everyone obeying did not happen before any other action in the second sentence (as there is no other action there). Lastly, been in the third example is impossible due to meaning (you are rarely watered unless you are a flower) and form as well: even if the passive voice could be used there, them would not ever follow watered, a finite verb that has only one transitive complement (tárgyi vonzat).

Another massive category of errors (about 17%) is that of the extra or wrong connectors which involves incorrectly using a connector (eg. which, that, where, if), or adding an extra word to a connector (eg. even if, as if, in which). Not a random one, though: a word that might occur next to the correct connector in a different context as part of a different phrase. This is why it’s under the label cat-and-another-cat: both meows but differently.

October 2009, Items 33-34

Given the fact that the words so and as can only follow each other naturally when using the structure so as (not) to, it is fairly easy to concede that it is either one or the other. Why so and not as? Well, as it is often the case with connectors, we have to consider the relationship between the two clause (ie. the two parts of the sentence) and decide which connector to use to express that.

In this particular case, we are looking at “Their home has since been fitted with special alarms (…)” and “Merlin should be able to sleep”. If we were to use as (expressing causality), it would imply that Merlin’s sleeping is a public interest and firefighters do really install special alarms just to avoid the end of the world with Merlin not sleeping. However, if we use so, we might make more practical sense: with the fire alarms installed, Merlin should be able to sleep at night.

May 2025, Items 29-30

As you may note, even though does truly exist, as do even and though separately; but it is fairly easy to say that even though, a subordinating connector would not really work here, as we only have one single clause in the sentence (one finite verb [have], one sentence).

Let’s now quickly decide which word to remove to make this work. Even is in a very natural position there, but we can’t tell the same about though; the most obvious way to add the latter to the sentence is at the end of it, or maybe as a discourse marker with commas around it (the family, though, have chickens…), breaking much of the natural flow of the sentence.

Last but not least, we should also discuss another significant category of errors: extra prepositions, such as the following:

October 2007, Item 40

October 2024, Item 27

Prepositions (ca. 16% of all errors) are sometimes very easy to miss: most of the times we are talking about two, three, maybe four letters altogether (eg. on, of, in, for), and another trick about them is that it is fairly easy to mask them as part of another grammatical structure. We see this in action in the first example where keen is followed by its usual complement on, but it is not preceded by a copular structure (cf. I am keen on learning English), but the possessive pronoun their, which would require a noun to follow after the adjective keen.

The second example for extra prepositions is very similar in that it also collides with a similar structure, two of them to be precise: mistake for, as the complement of the verb, and the time expressions with for often following Present Perfect structures (cf. I haven’t been here for a long time), maybe even for long as a collocation.

Before we turn to the most special cases, let’s just take a look at the distribution of the above error types over the last 20 years of the Érettségi:

Distribution of error types in error detection tasks

Explore the chart — hover over a slice for details.

Twin-cats for fun

Of course, no matter how hard we try to use the categories above, there will always be tricky lines which will be almost impossible to crack. Full disclosure: these lines really gave me a hard time too, starting with the first example:

October 2023, Items 26-28

These lines are especially hard, not because the relevant grammar rule requires some advanced language knowledge, but due to the plain fact that this is actually fully, completely, and entirely grammatical even with the word was in it.

“How’s so,” you may be asking, and rightfully so.

Let’s just go the way we would always do and make meaning to this sentence. So “I remember” is the main clause, and what do I remember? I remember that Dad burst through the front and was waving a book, so I can also say: “I remember Dad bursting though the front door” and “I remember (that) Dad was waving a book.”

Furthermore, I can also connect the two in a complex memory:

I remember (that) Dad burst through the front door, waving a book.

Or:

I remember Dad bursting through the door, waving a book.

However, I would argue that the comma before waving is very much necessary, especially if you want to add a third action to this series of events (shouting).

And this is where it gets interesting: you cannot add a comma in this task, you can only remove a word. But if you remove the word was from the original sentence, and end up with a trio of participle -ing clauses (bursting through the front door, waving a book, and shouting) and a comma that is very much needed to maintain the flow of the utterance.

But if the issue is with some commas, why can’t we insert one of them around bursting through the front door, which would result in a perfect English sentence with was in it:

Dad, bursting through the front door, was waving a book, shouting (…)

Or maybe, just maybe, let’s make it as natural as can be with removing was and adding and before shouting:

Dad bursting through the front door, waving a book, and shouting (…)

Am I arguing that the key of this task is wrong? Not necessarily. You can’t really inject a whole clause between the subject (Dad) and the main verb (was) without using some kind of punctuation. What I am arguing is that this sentence could have been easily phrased, so that there is less room for alternative solutions and interpretations:

I remember Dad bursting through the front door was waving a book, shouting, ‘You won’t believe what I’ve got!’

— Grammarly

I remember Dad bursting through the front door, waving a book, shouting, ‘You won’t believe what I’ve got!’

— QuillBot and LanguageTool

I remember Dad bursting through the front door, waving a book and shouting, ‘You won’t believe what I’ve got!’

— ChatGPT and Wordvice AI

(To make it even more problematic, consider the comma suggestion proceeding shouting.)

And not only this, but you also have to identify about 2-3 correct lines on average (ca. 2.45). But before you overthink this, I will give you a few tips on how to max out this task.

Tips and tricks

So, by an unfortunate turn of events, you are sitting in a room with 30-something other students taking the matura exam, and finally, you reached the error detection, the very last task in the Use of English part.

What do you have to do?

Other than identifying the unnecessary word or indicating that the line is correct, you may want to:

1. Slow down: First of all, put your foot on the brake. When reading for fun, we generally focus on meaning, understanding the text, collecting information and bridging gaps if needed. While doing so, we can easily skim through little spelling errors or, as in error detection tasks, unnecessary words.

2. Focus on grammar structures: Instead of focusing on meaning, try to focus on the little function words and don’t you ever forget: the devil is in the details. Read the sentence multiple times, stopping at every one of these little Satan’s minions.

3. Assume the sentence is wrong: As your mind wasn’t built for this, you have to flip your mind from understanding and make yourself find errors, instead of accepting the sentence as it is. In the first phase, you must ask yourself the question, “What is wrong with this sentence?”, and only after careful consideration would you be able to start asking the question “Is this sentence wrong?”

4. And notice your hesitation: After keeping yourself to the previous guidelines, you can start trusting your gut feeling. If you feel uncertain, strange, discomforted – you are halfway there. You just have to find which word makes you feel that way, and once you identified it, you can also try to read out the sentence without that word in it. If it works better or makes more sense without, you are good as gold.

Believe you me, if you use the categories as listed above and read the sentences carefully, word by word, you won’t have any issues with the error detection task. And on the bright side, remember that this task is always there in the Use of English part of the exam, so if you read this article, you are almost ready for one of the tasks that you’ll be writing soon. The rest is easy: practice, practice, and practice.