I am working on Infost 440 - Assignment 3 right now (double quotes)
I am working on $assignment right now (single quotes)

The different between double and singles quotes in php is that single quotes take everything in them as is/literally, so if you put a variable in there, it wouldn't print the value of the variable but just the variable name as you typed it. But for double quotes, it actually interprets everything (php elements like variables or operators) in them, so if you wrote a variable it would print the value instead of the name of it.