Question

What is the right way to write this an schedule or a schedule ?

Answer 1

a bus schedule

a punishing training schedule

a hectic/tight (= very busy) schedule

a schedule of talks at the convention(meeting)

 

The right way of writing a/an determiners coming from the following; The first thing that you should know is that there is no difference in their meanings. Secondly, we specificliy use "an" in our sentences before word that start with a vowel sound. On the other hand, we use "a" when they start with a consonant sound.

When you look more closely you see that it is really difficult to say "a hour" rather than  "an hour" ,or "an ball" rather than saying "a ball" .

Examples are taken from cambridge dictionary.

Answer 2

important that you know it is a SOUND rather than a spelling.  "h" is sometimes pronounced as a consonant..horse hotel.   sometimes it is silent, like.. hour, heir.   so it is AN hour.   AN heir.  but it is. ...A horror

Answer 3

'A' schedule is correct. 'An' is only used before a vowel sound.