Having difficulty remembering your minor second from your perfect fifth?
A useful method for learning the sounds of musical intervals is to think of famous pieces that make use of those intervals. For example, did you know that a perfect fifth is the first interval at the beginning of Twinkle, Twinkle Little Star? If you can sing the opening of that piece, you should be able to identify the same interval in other contexts.
Here then is a complete list of intervals together with famous pieces that begin with that interval: