First of all, we have to face the fact that schools -- classrooms -- are extraordinarily artificial environments. Groups of children, usually all the same age, follow instructions in order to solve problems that have no practical application except within the classroom itself. Furthermore, they usually work independently, often competetively, to attain a goal (a grade) that has little impact beyond a brief discussion with parents and teachers. By contrast, most environments outside the school group people without respect to age, and encourage cooperation within groups to accomplish a wide variety of tasks. Competition is more usually between groups than it is between individuals.
Now, there are aspects of childhood that are, from an adult standpoint, very artificial. Every boardgame you've ever played is in some sense artificial, and kids love them. Kids do, too, have a special affinity for other kids that are roughly their age. And there are steps in learning where it's very hard to find immediate, practical applications of problems, but you've got to learn them in order to be able to get to the next step. (Phonics is an example. You need it in order to be able to read, but the practical applications of phonics are limited, outside of the 1st grade classroom.)
But just because these artifacts are necessary at times doesn't mean that we need to make all of schooling march to that beat. We can, for example, encourage cooperative projects, because in adult life, cooperation is often key to the success of a project. Child rearing and scientific laboratory work have cooperation in common as keys to success. We can make some of the projects that kids work on be practical so that they can see that they are contributing to society (or their families or the running of the school). In that way they'll know that they are valuable, that they are necessary, that what they do MATTERS.
I think that making sure the students do work that MATTERS is probably the key. Everything else will follow from that. I don't mean service learning; that's a single method to the same end, but only a single method. For some students, doing something that matters might mean teaching them to cook and do childcare so they can help their working parents. For others it might mean teaching carpentry so that they can build playgrounds or fix school desks. For others it might mean taking internships with companies in the area in order to learn business skills within a real, operating business.
Not everything needs to matter. But that which matters is likely to wind up being a focus. Even *I* will sit in a classroom and learn something that I see as being important. And for kids, it's hard to understand that something is important unless you can see, now, that it matters to something you are doing NOW.
In the book Pricing the Priceless Child, the author follows the changes in society and law that took children from being economic assets to being liabilities. And it's true. Today, children are an economic drain on the family. If they were assets, yuppies would be married with children at the age of 18!
In an agricultural or hunter-gatherer society, children are only liabilities until they're about 6 years old. After that, they can start to contribute in ways that are necessary to the family's survival. Today they can't contribute until they are about 14 (depending upon the state's child labor laws) and instead are sent to school where they do NOT contribute to the family's welfare but, instead, learn skills so that they will be able to help, not their families, but themselves, later on.
Lucky children know that they are contributing to their families in other ways. They know that they are valuable because they are loved, and love is enough. But where they are not loved, or where they perceive that love is NOT enough (ie, to keep food on the table) then why should children find school rewarding?