Science teachers, like all teachers, start each school year with high hopes and expectations for students to succeed. They plan their lessons, scramble to get the necessary equipment, and work hard to engage their students. However, despite good intentions and best-laid plans, not all students do well in science classes, and even fewer achieve mastery. Student performance on national and international assessments is poor, and ,ore and more adults are unable to understand the scientific issues that affect their lives and society. Something must be done now to help science teachers put power behind their hopes and expectations for student achievement.