: Correctly place the indefinite article a or an in front of each word.

1. _____ hour
2. _____ octagon
3. _____ university
4. _____ banjo
5. _____ upperclassman
6. _____ hallway
7. _____ unopened box
8. _____ excellent bargain
9. _____ one-way street
10. _____ quarter-century

1. an hour

2. an octagon
3. a university
4. a banjo
5. an upperclassman
6. a hallway
7. an unopened box
8. an excellent bargain
9. a one-way street
10. a quarter-century

1. an hour

2. an octagon
3. a university
4. a banjo
5. an upperclassman
6. a hallway
7. an unopened box
8. an excellent bargain
9. a one-way street
10. a quarter-century

To correctly place the indefinite articles "a" or "an" in front of each word, you need to consider the sound at the beginning of the word.

1. _An_ hour - Since "hour" starts with a vowel sound (pronounced as "ow"), you use "an."
2. _An_ octagon - The word "octagon" also starts with a vowel sound (pronounced as "ok"), so you use "an."
3. _A_ university - "University" begins with a consonant sound (pronounced as "yu"), so you use "a."
4. _A_ banjo - Similarly, "banjo" starts with a consonant sound (pronounced as "b"), so you use "a."
5. _An_ upperclassman - "Upperclassman" starts with a vowel sound (pronounced as "uh"), so you use "an."
6. _A_ hallway - The word "hallway" begins with a consonant sound (pronounced as "h"), so you use "a."
7. _An_ unopened box - Since "unopened" starts with a vowel sound (pronounced as "uh"), you use "an."
8. _An_ excellent bargain - "Excellent" begins with a vowel sound (pronounced as "ek"), so you use "an."
9. _A_ one-way street - The word "one" starts with a consonant sound (pronounced as "w"), so you use "a."
10. _A_ quarter-century - "Quarter" starts with a consonant sound (pronounced as "kw"), so you use "a."

Remember, the choice between using "a" or "an" depends on the sound at the beginning of the word, not on the actual letter.