The definition of No Child Left Behind Act (NCLB) is a program instituted by the United States Department of Education under the George W. Bush administration to increase the performance of elementary and high schools without increasing spending on education. A steady decline in education quality measures over 50 years combined with a significant increase in education spending motivated the government to institute this program. Indeed, a startling number of students were graduating high school without knowing how to read and write.
Essentially, No Child Left Behind requires students to know certain skills and knowledge, in order to advance to the next grade. Some examples of this include basic reading comprehension and writing, basic mathematics skills, etc. Note that this does not mean that a certain grade point average is required, but rather standardized testing is used in conjunction with other methods to ensure that students acquire these basic skills.
Subsequent presidents, specifically, Barack Obama, have yet to take any action and No Child Left Behind and the policy remains in effect. There have been rumors that Obama may attempt to change the policy, but so far, the Obama administration has been focused on other issues such as the economy, healthcare, national security, and the war in Afghanistan. If the policy is not ended, there is a reasonable chance that it will be altered to some extent by the Obama administration and the new head of the Department of Education.