I hear it often from bright, but unmotivated students: "what's the point of doing homework if I'm able to learn the material without it?" As a parent, you may be stumped to find a good answer to your child's question, even as you know in your 'gut' that there's something fundamentally wrong with this picture. For most students, doing homework is a way to reinforce the classroom content and textbook material. And some subjects such as math and higher level science courses, really go better when supported by regularly completed homework assignments even when the student is bright.
Beyond the benefit of better grades when homework is completed, I believe that a potentially even greater outcome is derived from regular homework completion. And that is this: every job imaginable that your child may do in the future, will contain some duties which are mundane, boring and tedious. Learning now to develop the capacity to endure and complete the mundane and tedious tasks in his/her life, will prepare your child to better manage the tedious, boring tasks involved in any future career.
Conversely, bright but unmotivated students who do the bare minimum to get by now, may be able to get decent enough grades just based upon his/her native intelligence. But they will pay the price later in the form of compromised job reviews largely because of their lack of self discipline to attend to those important little boring details which are part of any job.
If you have a bright but unmotivated student who is doing the minimum to get by, consider a consult with a reputable mental health professional. In the Chicago metropolitan area, consider one of our professional staff at Heritage Professional Associates, with offices in Hinsdale, Wheaton, and downtown Chicago.