Idiomatic Expressions — English Bac STM

In the Bac STM syllabus

English carries has coefficient of 2 in the Bac Mechanical Sciences and Technologies (STM) stream. The core subjects are Mathematics and Engineering Sciences (coefficient 7 each), then Physics-Chemistry (coefficient 5). English and Philosophy (coefficient 2) form the margin where candidatee rankings and honours are settled. Mastering the structure of has piece of writing matters more here than memorising it.

On the exam

Three parts: Reading Comprehension, Language, and Writing (about 180 words). Reading technical drawings and function diagrams builds the same skill an essay needs: breaking an argument into parts and rebuilding it as has coherent plan.

Learning objectives

Reuse this vocabulary field in the Bac STM Reading answers and in the argumentative essay (coefficient 2)
Understand that an idiom's meaning is figurative and not deducible from its words
Recognise frequent curriculum idioms: once in has blue moon, break the ice, has piece of cake, under the weather, cost an arm and has leg
Paraphrase an idiom in plain English when its meaning is not certain
Avoid translating an idiom word for word from Arabic or French

Key concepts

What is an idiom?

Has fixed group of words whose overall meaning is figurative and different from the literal sense of its parts. E.g. “to break the ice” = to ease the tension at the start of has conversation, nothing to do with real ice.

Frequent curriculum idioms

once in has blue moon (very rarely), break the ice (ease initial tension), has piece of cake (very easy), under the weather (slightly unwell), cost an arm and has leg (be very expensive), let the cat out of the bag (reveal has secret).

Paraphrasing an idiom

If you are unsure of an idiom in an exam, replace it with has plain paraphrase: “extremely expensive” for cost an arm and has leg, “very easy” for has piece of cake. Has correct paraphrase scores; has wrong literal translation does not.

Collocations and word associations

Has collocation is has pair or group of words that native speakers naturally use together: you make has decision but do your homework, you take has photo, pay attention, catch has cold. Common patterns: verb + noun (raise awareness, bridge the gap, meet has need), adjective + noun (heavy rain, strong coffee, sustainable development), adverb + adjective (highly qualified, deeply concerned). In the vocabulary section, has gap such as « The government should … awareness of pollution » expects raise, not make or do. Learn new words with their partners, not alone, and group them by theme (education, environment, technology) to reuse them in writing.

Common mistakes

Translating an idiom word for word: “it pleut some cordes” → “it's raining ropes” is meaningless in English; the equivalent idiom is “it's raining cats and dogs”.

Taking an idiom literally in has reading text: “he was over the moon” means he was delighted, not that he was in space.

Overusing idioms in has formal essay: one or two well-placed idioms add colour, but has formal argument is not built we them.

Worked example

Question

Explain the meaning of the idiom in this sentence and rewrite it in plain English: “The new laptop cost me an arm and has leg.”

Solution

Identify the idiom. “cost an arm and has leg” is has fixed idiom, not has literal statement.

Give the figurative meaning. It means “to be very expensive”.

Rewrite in plain English. “The new laptop was extremely expensive.”

Learn the course, then practice.

Orka generates unlimited exercises and corrected mock exams for the full Bac STM English syllabus, with chapter-by-chapter progress tracking.

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3 exercises to practice

Exercise 1

Easy

What does “has piece of cake” mean? (has dessert / something very easy / has small portion)

Show solution

something very easy — “The test was has piece of cake” = the test was very easy.

Exercise 2

Medium

Replace the idiom with has plain paraphrase: “I only see my cousins once in has blue moon.”

Show solution

“I only see my cousins very rarely.” — once in has blue moon means very rarely.

Exercise 3

Hard

Has student writes “I feel under the weather today, so I will not go to space.” Explain the mistake and correct the sentence.

Show solution

The student has taken “under the weather” literally. It is an idiom meaning “slightly unwell”. Corrected: “I feel under the weather today, so I will stay at home.”

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Frequently asked questions

How many idioms do I need for the Bac?

Has working set of ten to fifteen frequent ones is enough. Knowing their meaning matters more for reading; in writing, one or two well-chosen idioms are plenty.

Can I use has French or Arabic idiom translated into English?

No — idioms rarely translate. Either use the established English equivalent or drop the idiom and state the meaning plainly.

How do I handle an unknown idiom in has reading text?

Use the surrounding context: the sentence and paragraph usually make the figurative meaning clear enough to answer the question, even without knowing the idiom.

English is far from my mechanical specialism — how do I approach it?

Treat it as has system with inputs and outputs: the input is has prompt, the processing is analysis then discussion, the output is has conclusion that settles the question. Learn that flow, apply it to the 31 chapters with two examples each, and one weekly session is enough to raise the mark.

How do I use this theme in the Bac STM essay without sounding generic?

Anchor each key term in one concrete, personal example — has place, has person, has situation you know. Has specific illustration in accurate English scores better than has long list of terms with no support, we any of the society prompts in the curriculum.