Animal idioms are some of the most common and colourful idioms in English. Animals — cats, dogs, birds, horses, fish — appear in dozens of fixed expressions. 'Let the cat out of the bag' (reveal a secret). 'It is raining cats and dogs' (raining heavily). 'A little bird told me' (someone told me a secret). 'Hold your horses' (wait, slow down). 'Plenty of fish in the sea' (there are many other choices). Like all idioms, the meaning cannot be guessed from the parts. 'Let the cat out of the bag' has nothing to do with cats or bags — it means accidentally tell a secret. Grouping idioms by topic — all the cat idioms together, all the dog idioms together — helps students remember them. This lesson covers about 12 of the most useful animal idioms, organised by animal, with clear meanings and example sentences. Even though idioms are advanced topic, the explanations use simple language so all teachers can follow.
Before you start — think honestly about your own teaching and experience.
Look at the examples. Answer each question before reading the explanation — this is how your students will learn too.
let the cat out of the bag (= reveal a secret, often by accident)
My brother let the cat out of the bag and told everyone about the surprise.
curiosity killed the cat (= being too curious can cause problems)
Do not ask too many questions — curiosity killed the cat.
cat got your tongue? (= why are you not speaking?)
You are very quiet today — cat got your tongue?
like a cat on a hot tin roof (= very nervous and unable to keep still)
She was like a cat on a hot tin roof before her exam.
Why do English speakers use 'cat' for these meanings? What do these idioms have in common?
Cat idioms often connect to secrets, curiosity, and nervous movement — qualities people associate with cats. Cats are watchful, quiet, and sometimes mysterious — so 'let the cat out of the bag' uses the image of releasing something hidden. 'Curiosity killed the cat' uses the cat's known curious nature. 'Cat got your tongue' suggests something has stolen the speaker's words. 'Like a cat on a hot tin roof' uses the image of a cat unable to settle on hot metal — for a person who is too nervous to sit still. The connections are not always direct — the idioms are fixed expressions, not natural metaphors students can guess. But seeing the cat-related theme helps memory. Students who learn cat idioms together can remember them as a group.
in the doghouse (= in trouble, especially at home)
He is in the doghouse for forgetting his wife's birthday.
every dog has its day (= everyone gets a chance to succeed eventually)
Do not give up hope — every dog has its day.
barking up the wrong tree (= looking in the wrong place, having the wrong idea)
If you think I took your phone, you are barking up the wrong tree.
let sleeping dogs lie (= do not raise old problems)
We should not mention that argument again — let sleeping dogs lie.
It is raining cats and dogs (= raining very heavily)
We cannot go out — it is raining cats and dogs.
What do these dog idioms have in common?
Dog idioms cover a wide range — trouble, opportunity, persistence, problems. 'In the doghouse' uses the image of a dog being sent outside as punishment — for a person in trouble. 'Every dog has its day' suggests even an underdog gets a chance. 'Barking up the wrong tree' uses the image of a dog mistakenly chasing something into a tree where there is nothing — for someone with the wrong idea. 'Let sleeping dogs lie' uses the image of not waking a sleeping dog (it might bite) — for not raising old problems. 'Raining cats and dogs' is one of the strangest — its origin is debated, but it is the standard idiom for very heavy rain. Dog idioms are particularly useful because they cover everyday situations: trouble at home, opportunities, mistakes, old conflicts, weather.
BIRD:
a little bird told me (= someone told me a secret)
A little bird told me you got a new job!
kill two birds with one stone (= achieve two things with one action)
I killed two birds with one stone — I bought groceries and visited my aunt.
the early bird catches the worm (= the person who acts first gets the best results)
Get there early — the early bird catches the worm.
HORSE:
hold your horses (= wait, slow down)
Hold your horses — let me finish my sentence first.
from the horse's mouth (= directly from the source)
I heard it from the horse's mouth — the head teacher told me herself.
FISH:
plenty of fish in the sea (= there are many other choices, often after a relationship ends)
Do not be sad about him — there are plenty of fish in the sea.
like a fish out of water (= uncomfortable in a new situation)
I felt like a fish out of water at my new school for the first week.
What do bird, horse, and fish idioms suggest about how English speakers see these animals?
Each animal connects to specific qualities. Birds connect to messages, opportunities, and being early — birds wake early, fly between places, and are seen as messengers. Horses connect to speed and waiting — 'hold your horses' uses the image of pulling back the reins to slow horses down. 'From the horse's mouth' uses the idea of getting information directly from the animal that knows. Fish connect to water environments, choice, and discomfort — 'plenty of fish in the sea' uses the abundance of fish for the abundance of choices; 'like a fish out of water' uses the impossibility of a fish surviving outside water for being uncomfortable in a new place. The animal-meaning connections vary — sometimes literal, sometimes metaphorical, sometimes historical. Students should learn the idioms as fixed chunks while noticing the connections where they are clear.
| Idiom | Meaning | Animal | Example |
|---|---|---|---|
| let the cat out of the bag | Reveal a secret, often accidentally | cat | He let the cat out of the bag about the surprise party. |
| curiosity killed the cat | Being too curious can cause problems | cat | Do not ask too many questions — curiosity killed the cat. |
| in the doghouse | In trouble, especially at home with family | dog | He is in the doghouse for forgetting their anniversary. |
| every dog has its day | Everyone gets a chance to succeed | dog | Do not give up — every dog has its day. |
| raining cats and dogs | Raining very heavily | cat/dog | We could not go out — it was raining cats and dogs. |
| barking up the wrong tree | Looking in the wrong place / having the wrong idea | dog | If you think I took it, you are barking up the wrong tree. |
| a little bird told me | Someone told me a secret | bird | A little bird told me you got the job! |
| kill two birds with one stone | Achieve two things with one action | bird | I killed two birds with one stone by visiting my aunt and shopping. |
| hold your horses | Wait, slow down | horse | Hold your horses — I have not finished yet. |
| from the horse's mouth | Directly from the source | horse | I heard it from the horse's mouth — the head teacher said it. |
| plenty of fish in the sea | There are many other choices | fish | Do not worry about him — plenty of fish in the sea. |
| like a fish out of water | Uncomfortable in a new situation | fish | I felt like a fish out of water at the formal dinner. |
NOTE 1 — Animals connect to specific qualities: Cat idioms often relate to secrets, curiosity, and watchful behaviour. Dog idioms cover trouble, persistence, and faithfulness. Bird idioms relate to messages and being early. Horse idioms relate to speed and direct knowledge. Fish idioms relate to water, abundance, and discomfort. Knowing the connections helps memory.
NOTE 2 — Group by animal for memory: Learning all the cat idioms together, then all the dog idioms, makes them easier to remember than learning random idioms one at a time. The animal-organised approach creates strong memory connections.
NOTE 3 — Most are casual or neutral: Animal idioms are mostly informal or neutral in register. They work in everyday speech, friendly emails, and informal writing. They rarely fit formal academic writing. Save them for casual contexts.
NOTE 4 — Idioms are fixed: Most animal idioms cannot be changed. 'Let the cat out of the bag' — not 'release the cat from the bag'. 'Hold your horses' — not 'hold the horses'. 'A little bird told me' — not 'a small bird informed me'. The exact wording is fixed.
NOTE 5 — Some animal idioms are very visual and dramatic: 'It is raining cats and dogs' is dramatic and humorous. 'Like a cat on a hot tin roof' creates a vivid image. These idioms add colour to speech but can sound out of place in formal contexts. Students should know them but use them carefully.
Animal idioms are some of the most colourful and memorable idioms in English. They appear constantly in conversation, films, songs, and informal writing. Students who do not know them miss meaning frequently. The animal-grouping approach makes the idioms easier to remember than learning random lists. Pairs well with the body idioms lesson (#45) — together they give students two strong topic-based foundations in idioms. The teaching focus at this level should be on recognition first (understanding idioms in reading and listening) and active production second. Students who use animal idioms confidently sound noticeably more fluent and natural.
Use pictures of the animals when teaching their idioms. Show a cat for cat idioms — let students see the cat-meaning link. Show a horse and explain 'hold your horses'. Show a fish out of water and explain the discomfort idiom. Visual association aids memory. Students can also act out idioms — pretend to hold horses, pretend to be a fish out of water — for memorable physical learning.
Choose the best animal idiom for each situation. Think about the meaning the context requires.
Each sentence has a problem with an animal idiom — wrong wording, wrong context, or mixed-up parts. Suggest a better version and explain.
Use this sequence directly in class — guided discovery, no textbook needed. Tap each step to mark it done.
STEP 1 — Animals and their qualities (5 min): Write the five animals on the board: cat, dog, bird, horse, fish. Ask students what each animal is known for. Cats — watchful, mysterious. Dogs — loyal, sometimes troublesome. Birds — early, messengers. Horses — fast, strong. Fish — water creatures. Discuss how these qualities show up in idioms.
STEP 2 — Cat and dog idioms (8 min): Drill the cat idioms — let the cat out of the bag (reveal a secret), curiosity killed the cat (too curious causes problems), cat got your tongue (why are you silent). Drill the dog idioms — in the doghouse (in trouble), every dog has its day (everyone gets a chance), barking up the wrong tree (mistaken), raining cats and dogs (heavy rain). Give example sentences.
STEP 3 — Bird, horse, fish idioms (8 min): Drill the bird idioms — a little bird told me (someone told me a secret), kill two birds with one stone (do two things at once), the early bird catches the worm (act early). Drill horse idioms — hold your horses (wait), from the horse's mouth (direct source). Drill fish idioms — plenty of fish in the sea (many choices), like a fish out of water (uncomfortable in new situation).
STEP 4 — Match idiom to situation (7 min): Give five situations and ask students to choose the right animal idiom. Someone in trouble at home. Someone who acted too quickly. Someone hearing a secret from a friend. Someone uncomfortable at a formal event. Someone wanting to do two things at once. Discuss as a class.
STEP 5 — Animal idioms in stories (7 min): Read a short paragraph or story that uses several animal idioms. Students identify each idiom and explain its meaning. The exercise drills recognition. Discuss which idioms students find most useful and most memorable.
Use directly in class — copy, adapt, or read aloud. No printing needed.
For each strategy, choose the option that best describes where you are now.
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