Articles help please!

[user789653241]

My ds asked me a question about articles. He said " a unicorn" sounds right, and " an unicorn" sounds wrong.

I said to him that an comes before "vowel sound" and a comes before consonant sound, so even "unicorn" starts with "u", actual sound is "y", so the article should be "a".

Then I got a bit confused. How about things like "ape" or "acorn"?
Is it a vowel sound or consonant sound?
I am a foreigner, although I do understand some rules in English, it's not certain. I kind of get it instinctively, but become really unsure if I think about something.
Can someone please explain to me how articles work, so I can explain to my ds better?

Rather than look at the letter think about the sound you can hear at the beginning of the word (as you did instinctively with unicorn) if it has a vowel sound it's an ...an acorn, an ape, an hour ...if it's a consonant sound it's a ..a cat, a house, a unit

Thank you mrz.
Ds asks unexpected questions when least expected.
So it's always depend on letter sound right after articles?

1: a professional artist, not an professional artist?
2: a bag of oranges, not an bag of oranges?
I can feel 2 is wrong to be " an ", but not sure about first one.
I mean, articles doesn't depend on the noun it is referring to?

1: a professional artist, not an professional artist?
2: a bag of oranges, not an bag of oranges

Correct

Thank you.
I think I will go with my instincts for now.
I am sure he will get far better with English grammar than myself soon, since his only language is English.

(It's so frustrating to communicate with my own child with my secondary language though... )

Basically it sounds clumsy to say a octopus or a onion so we substitute an an octopus, an onion, an orange car, an interesting book etc

That really makes sense. Thank you again!