Is it this year or last year?

I engaged in a very confusing conversation with my 8-year-old son today. We were talking about baseball season, which ended in June. I made a comment about "this year's baseball team" and my son tells me that was "last year." I explained to him about how baseball season ended less than six months ago and it was 2007 then and it's still 2007, so it was "last season," not "last year." He then goes on to say that he was in 1st grade "last year" when he was playing baseball, and now he's in 2nd grade. I have to further explain that the school year actually starts in one year and ends in the next year, but it's different than the "calendar year." Oh my goodness! This had my poor child thoroughly confused and frustrated. And of course we're having this conversation while in the vehicle, so I can't just show him a calendar and make things more concrete for him. I ended up with a major headache and he still doesn't get it. I'm not so sure I want to bring it up again either.