In many U.S. high schools, Advanced Placement is treated like the family china, brought out only for special guests. This is gate keeping-faculty-room jargon for offering hard courses only to the best students and finding something easy for everyone else. It occurs in most American high schools and is usually justified, like bunny slopes for uncertain skiers, as a way to save ill-prepared students from crashing into mountains reading lists. Yet visits to 75 schools and data from thousands of others suggest that the practice is severely misused and overused, and can be balanced for much of the low motivation and achievement spotlighted in a recently released international survey of high-school math and science skills. AP tests were designed more than 40 years ago by the College Board for ambitious students who wished to earn college credit in secondary school. They were first given only in private schools and the most competitive public schools, but by 1996 more than half of all U. 8. High schools had joined the program, giving 843,423 AP tests in 18 subjects to 537,428 students. Many educators say the AP and the much less common but similarly challenging International Baccalaureate tests should be reserved for the very best students. Less gifted students ask simplistic questions and slow the pace, they say, cheating the quicker minds for which the tests were originally designed. This reluctance to stretch young minds has many roots. Some teachers say that students asked to do hard work will lose interest in school altogether and drop out. Some complain that parents protest difficult lessons, especially when potentially bad grades threaten college chances. Some teachers, already drained by long hours teaching ordinary classes, do not think they have the energy to pull students up to AP level. Some principals and department heads wonder if they have enough teachers who are willing to be judged by their students’ performance on national examination. Many educators say the AP and the much less common but similarly challenging International Baccalaureate tests should be reserved for the very best students. Less gifted students ask simplistic questions and slow the pace, they say, cheating the quicker minds for which the tests were originally designed. Here and there, a few students are beginning to see gate keeping as pedagogical malpractice. In 1995 Kerry Constable at Mamaroneck High responded in an extraordinary way to a refusal to let her take AP American history: she assigned herself the course. Constable bought one of the commercial guides to AP history, with sample tests. She found information on the Internet. Students in the AP course gave her copies of their exercises. Friends shook their heads in amazement when they found her in the library, doing homework no teacher had told her to do. When she passed the AP test, classmate David Abramowitz wrote a needling editorial in the school paper: “If our school really wants students to achieve their maximum potential, then it shouldn’t deny them the opportunity to learn more and work harder.” Educators waving students away from the most taxing courses mean no harm. But their kindness is akin to keeping a tottering infant from taking his first dangerous step. As every parent knows, babies have to stumble before they can learn to walk.