In Reading, first you see it, then you hear it.
In Spelling, first you hear it, then you see it.
When a student learns reading, this skill requires instruction on the print such as the name and speech sounds of letters needed in order to make words. This knowledge will, in turn, help the students with the meaning of those words.
But when a student is learning to spell, the spelling information, will, in turn, help the students memory of words that will be used in both spelling and sight reading.