1. It is a quarter past seven.
2. It is a quarter after seven.
3. It is a quart to seven.
4. It is a quarter before seven.
(#1 is the same as #2, right? #3 is the same as #4? Why is 'to' used here in #3 instead of 'before'?)
Yes, you are correct. #1 and #2 both mean the same thing, which is "It is 15 minutes past seven." Similarly, #3 and #4 also convey the same meaning, which is "It is 15 minutes before seven."
The reason why #3 uses "to" instead of "before" is a matter of preference and regional variations. In some English-speaking regions, such as the United States, "before" is commonly used to indicate time occurring prior to a specific hour. However, in other regions like the United Kingdom, "to" is often used instead of "before" when referring to time leading up to the next hour. So, both phrases are correct and understandable, but their usage can vary based on location and personal preference.
# 1 and 2 are the same.
If 3 is "quarter to seven," then 3 and 4 are the same. We don't usually use # 4, though.
For this meaning, "to" and "before" have the same meaning.
As a native English speaker, I can't really explain all of the nuances of our prepositions.