Indefinite articles

In English, indefinite articles are: a/an.
We use a before consonant sounds: a pen      a desk      a teacher
We use an before vowel sounds:   an apple      an ice cream        an opera

ACTIVITY
Write a or an.
____ cat
____ dog
____ owl
____ footballer
____ glass
____ egg
____ film
____ telephone
____ umbrella
____ train
____ opera singer
____boy
____ girl
____ island
____ exercise book
____ activity