I feel the pain! This is a very frequent phrase heard around my school, and something the staff is constantly working against. However, nothing seems to have worked as of yet.
At my school in particular students do not see the value of an education, especially post-secondary. Despite teachers telling them that more education means better pay, better jobs, etc. these students don't see it. All they see are their relatives (many of whom are immigrants) who have very little education making "decent" money. I get the, "so what if I don't graduate? I'll just go work with my uncle" speech.
And unfortunately for those who do pass, those low marks will not get them accepted into any post-secondary institutions, so it's almost like it's not worth the effort.
The only saving grace is that the truly "academic" students do put at least some value in their work and attempt to get good grades. It is those who struggle in school who don't see the value. Maybe it's all tied to past achievement and that feeling of "getting it."