A and an

 "A" and "an" are indefinite articles in English. They are used to refer to a non-specific or unknown noun, and are always placed before a singular noun. The choice between "a" and "an" depends on the sound of the first letter of the noun.

Here is a chart to help explain:

Indefinite Articles	Before a vowel sound	Before a consonant sound
"A"	"an umbrella"	"a car"
"An"	"an apple"	"a book"

As you can see, "a" is used before a consonant sound, while "an" is used before a vowel sound.

Here are some examples:

• I need a pencil for class.
• An elephant is a large animal.
• A boy is playing in the park.
• An orange is a fruit.
• A doctor helps sick people.
• An umbrella is useful in the rain.

Exercise: Fill in the blanks with "a" or "an" in the following sentences:

1. __ book is on the table.
2. She is eating __ apple for a snack.
3. He drives __ car to work every day.
4. We saw __ elephant at the zoo.
5. She needs __ umbrella because it is raining.
6. He is __ doctor and helps people who are sick.
7. I want to buy __ orange at the store.