Tense and aspect are often mixed up by coursebooks. There isn't really much agreement on the issue- many coursebooks treat aspect as tense. I think things are a lot simpler and clearer if we think of English as having two tenses and two aspects, but books still keep coming out giving a different picture of language. The difficulties in this area, where the terminology isn't even standard (progressive vs continuous) so it is little wonder that students get tense and aspect mixed up. With a general consensus on how many tenses there are, etc, I think that the rather messy view of the verb will continue. This is one area where not having a body like the Academie Francaise to decide on such issues is a disadvantage in my opinion.