They want to extend the 'length' of the school year. [=to make the school year longer; to lengthen the school year]
I've been/traveled 'the length and breadth of' the canyon, but I still haven't found the caves I'm looking for.
I managed to swim four 'lengths' of the pool. [=to swim from one end of the pool to the other end four times]
(..) Then something crazy. That's more like it. Sound your positions. Stay within earshot. - Here! - One length to your stern. Listen, Stoick, I was overhearing some of the men and, well, some of them are wondering what it is we're up to here. Not me, of course. I know you're always the man (..)2010 How to Train Your Dragon