Top 15 commonly used idioms | Part 1

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Regarding the Duolingo English Test, from our nearly 20,000 students in the last 12 months, we have researched and got some commonly used idioms in different topics to help test-takers (both DET and PTE takers) get higher scores in Speaking and Writing questions.  

Before exploring the top 15 commonly used idioms, do you know what grading elements evaluate your vocabulary in the Duolingo English Test?

There are two grading elements: Lexical Sophistication and Lexical Diversity

• Lexical Sophistication evaluates the level of vocabulary used. If you use idioms or high-level words (B2, A1, A2), it’s always better than using single A1, A2, or B1 words. For example, the word “expensive” can be used in uncountable scenarios. Do you know any idioms or other high-level words that we can use instead? To name a few, we have “cost an arm and a leg”, “exorbitant”, “overpriced”, and so on. 

• Lexical Diversity evaluates the variety of word choices. If test-takers face a topic that they can use the word “expensive”, please DO NOT use that word over two (02) times. There are so many synonyms for the word “expensive” that we need to use instead. Some more synonyms for “expensive” are “costly” and “extravagant”.  

We admit it, it’s not easy to use idioms or high-level words if we don’t practice using them regularly. There is no way to utilise them unconsciously and effectively during our tests if we don’t put effort into practising. Luckily enough, the top 15 commonly used idioms we are about to share are super common and easy to remember. What test-takers need to do is apply them to practice right away on the DET Practice Platform after completing this article because it's the best way to learn how to use them in specific questions – learn through doing. 

If you are ready, let’s get into it.

1. Cost/Pay an arm and a leg

• Meaning: to cost/pay a lot of money
• Example: That watch costs an arm and a leg.

This idiom is considered one of the most common ones as it can be used in multiple topics such as Shopping, Travelling, Investment, Education, and so on.  

For example, here is one Read then Write question on the DET Practice Platform – TADE Hub.

Regarding this question, it’s about Investment, Art and Education. Thus, in our Body paragraphs, we may write something as follows in this Read then Write sample question: “In modern society, the cost of education is gradually increasing day after day. Students have to pay an arm and a leg to some sources in order to enrol. Therefore, the government should invest more in education to make it more accessible to more citizens, especially low-income individuals and families.”

2. Hit the books

• Meaning: To start studying seriously
• Example: I cannot go, I have to hit the books for next week's exam. 

Test-takers apparently can use this idiom in School, Education, Skill Gaining, Dreams, or other topics if they face them in the Duolingo English Test. The below image is a Read then Speak sample question. 

The question is about a goal that we hope to achieve in the future. We can use “Hit the books” to answer the 3rd or 4th minor questions. Let’s go with the 3rd one in this Read then Speak sample question: “Mastering the Public Speaking skill is no joke, we need to have a step-by-step plan to frequently keep track of our progress. The first step of my goal is to finish reading the top three books about Public Speaking to gain the most fundamental idea and knowledge of it in one month. As a result, I need to hit the books carefully for an effective outcome.”

3. A piece of cake

• Meaning: a thing that is very easy to do
• Example: Doing chores is a piece of cake.

A piece of cake can be applied to countless topics including describing images in Write About the Photo or Speak About the Photo. In this image sample, we can say something like: “Three people are doing yoga effortlessly, it looks like a piece of cake to them.”

4. Not somebody’s cup of tea

• Meaning: not what somebody likes or is interested in
• Example: An evening at the opera isn't everyone's cup of tea.

This is also a very common idiom that people use most of the time even in their daily conversations. If we apply to our Speak About the Photo question, we could say “Someone is pouring beer into a cup, and there are two other people in the background talking to someone else to their right. It looks like they are having a party with lots of beer. Nevertheless, drinking beer is not everyone’s cup of tea.”

5. Call it a day

• Meaning: to decide or agree to stop doing something
• Example: After fifty years in the agriculture industry, I think it’s time to call it a day (to retire).

Call it a day can be applied to various types of topics such as Travel, School, Job, Favorite hobbies, and so on. Our sample question, asks about your favourite movie or TV series, we can answer this Writing Sample question as follows: “My favourite movie is Oppenhemmer that I watched with my girlfriend. On that day, I had lots of tasks at work, but in the end, I called it a day and went back home early to watch the movie with my girl.”

6. Once in a blue moon

• Meaning: Very rarely
• Example: It is once in a blue moon that he works out.

We use Once in a Blue Moon as an adverb of frequency, so it is super easy to put it into our conversation or writing. If we apply to the above Speaking Sample question, we may say “It was once in a blue moon that I spent a bunch of money on something, so I recall it very well.”

7. Trial and error

• Meaning: the process of solving a problem by trying various methods until you find a method that is successful
• Example: It took us nearly five years of research as our approach is by trial and error. 

Trial and error is a great way to express something like “In order to achieve this, I have tested many methods and failed countless times until it succeeded”. Thus, how do you apply to our Speaking Sample question? Here is ours “After receiving our 1st place reward in our school innovation program, we celebrated with a huge party overnight because we had worked for 10 months continuously to find the best innovative idea by trial and error.”

8. A night owl

• Meaning: a person who enjoys staying up late at night
• Example: A friend of mine is a real night owl. He stays up late until 2 AM almost every day.

A night owl can be used any time in any topic if you want to say someone stays up late. That is it. Here is how we apply this Read then Write question: “To illustrate, if I send a letter with my handwriting to my crush, it is more valuable than sending texts to her. If I’m not mistaken, there was one night last month that I became a night owl wrote a letter and sent it to my crush to show my love. She was impressed and accepted my proposal to be my girlfriend.”

9. An early bird

• Meaning: a person who gets up, arrives, etc. very early
• Example: I prefer to be an early bird rather than a night owl.

Similar to A night owl, we can surely use An early bird in most cases to say that we wake early in the morning. Regarding our Read then Speak question, we can answer like this: “The first step is to get familiar with the writing process, so I am recently an early bird practising writing almost every day a week.”

10. Kill two birds with one stone

• Meaning: to achieve two things at the same time with one action
• Example: Our recent campaign acquired more than five thousand new users and won an annual award. We killed two birds with one stone.

To practice using new idioms, we need to apply them in topics that they are used the most. In this case, Killing two birds with one stone can be used in Business, Objective, School, and so on. However, if your English is at a high level you will be able to use it in most case scenarios as long as you comprehend its meaning. Hence, in our Read then Speak question, this is how we answer: “I have been working my tail off for over 12 months, so I decided to call it a day and drove to Ho An Ancient town for a week. Ho An Ancient town is historically beautiful, and it has been my dream to visit since a child. So this trip killed two birds with one stone.” 

11. Don’t count your chickens (before they are hatched)

• Meaning: you should not be too confident that something will be successful, because something may still go wrong
• Example: Until they make the payment, don’t count your chickens. 

This is a pretty awesome idiom to show that nothing is 100% certain until it actually happens. How would you apply this idiom to our Speaking Sample question? Check ours here: “Our family was excited for months preparing for our vacation in summer. But unfortunately, when the time came, a precipitously unforeseen storm destroyed everything. We had booked hotels, resorts, and tours, but they were all gone for nothing. After that disastrous event, I told myself, don’t count your chickens before they are hatched.”

12. Over the moon (on cloud nine)

• Meaning: Extremely happy and excited 
• Example: I was over the moon when I got over 145 overall DET scores.

Here we come to an idiom to show our happiness. If you feel happy, let’s use Over the Moon or On Cloud Nine instead. To apply to our Read then Speak question, this is how we use it: “When I got back home, the whole family already decorated all the walls, prepared my birthday cake in addition to other foods to celebrate my birthday. I had nothing to say, actually, I couldn’t express myself with my words because I was just simply on cloud nine.” 

13. If my memory serves me right

• Meaning: If I remember correctly 
• Example: If my memory serves me right, it was at the end of 2022.

When you are not sure if you remember something correctly, we use “If my memory serves me right” to start our speech or writing. Let’s apply to this Read then Speak sample question: “If my memory serves me right, it was at the end of 2021 when I for the first time did rock climbing in my pastime.”

14. (put something) In a nutshell

• Meaning: to say or express something in a very clear way, using few words
• Example: To put it in a nutshell, we achieved our objective this year.

After a long explanation, and we want to use fewer words to conclude it, then we need to start with “In a nutshell”. Here is our simple application to this Writing Sample question: “In the age of modernization and the internet, online training programs from variously prestigious institutions are offered to students worldwide as we are living in a flat world where people, as long as they have access to the internet, are able to learn in a school thousands of miles away from their country of origin. On top of that, the quality of online programs is no different from offline education, therefore, it is more convenient for students to pursue this type of program nowadays. To put it in a nutshell, it’s entirely possible to get a good education online.” 

15. All in all 

• Meaning: when everything is considered
• Example: All in all, we need to fly to Vietnam to see our parents. 

DET takers can use All in All to conclude their writing for reading then Write and Writing Sample all the time. For other Speaking question types, it depends on the topic to see if it’s suitable to deliver or not. In this Read then Write sample question, we may write: “All in all, school teachers and parents should be accountable equally to support a child’s upbringing both in social and intellectual aspects.”

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If we already learned all the 15 commonly used idioms, it’s time to put them into use. While practising on the DET Practice Platform, users get instantly detailed feedback for all question types, especially Writing and Speaking questions. For instance, if DET takers practice a Write About the Photo question, the system offers instant feedback based on Fluency, Grammatical Accuracy, Lexical Sophistication and Lexical Diversity. Soon enough, we will be evaluating your Grammatical Complexity and Relevance to cover all DET grading elements to deliver more accurate feedback.

Let’s take a look at this video sample feedback for a better understanding. Go visit our DET Practice Platform and start practising all idioms.