I guess I agree with Bostonian to a degree. By the time students are ready for this lesson about the brain and its supposed muscle-like qualities, the brain's development has already slowed considerably. In the early years, environmental stimuli and challenges can significantly impact development, but once that window has passed, I'm not inclined to pretend otherwise. These students may be working in an effort to make themselves smarter, but what they are really doing is making themselves more knowledgeable.
Why not be honest about the situation? Knowledge can be very rewarding, and is often a prerequisite for understanding.
My oldest child isn't 3 yet, but when the time comes, I think I'll explain to her that her intelligence is like a multiplier for her effort. Performance = Effort X Intelligence. Since she appears to have a high intelligence, she can manage a mediocre performance with very little effort. However, if she wants to perform at the highest level, considerable effort will be required.
