This article reports that in 1996, Alabama officials approved the "4 x 4" plan, which made their state the first in the country to require students to complete four years, or four credits each, of math and science for high school graduation. Other states have since followed suit, with policymakers arguing that higher standards are necessary to gird students for increasing demands from colleges and employers and to cultivate a capable workforce. Alabama officials decided last year to set an even loftier goal: All entering 9th graders in 2009 must pursue an "advanced" diploma, meaning they have to complete Algebra 2, including trigonometry content, unless their families let them opt out of that mandate. That requirement will mean that Alabama, which has traditionally lagged near the bottom of all states on national tests of academic progress, has established one of the more demanding math standards in the country. Yet Alabama's experience with its 4 x 4 plan underscores the challenges states face in implementing such requirements. Different public schools in the state have taken very different approaches to meeting the mandates, depending on such factors as course scheduling and the needs of their student populations. In some Alabama schools, students meet the four-year requirement by taking at least one math and science class each year, 9th through 12th grades. In schools that use block scheduling, students take extended classes lasting about 100 minutes. They receive one credit for a half-year of classwork. That allows some students to complete four years of math and science in two or three academic years. In some schools, students may not take math during certain half-year terms, as long as they are progressing toward obtaining the necessary four credits before graduation.