The No Child Left Behind Act set national standards for student progress and an annual testing regime to measure it when the federal law was passed in 2002.
The charts presented represent the progress local school districts have made in achieving those standards in the past six years. The data comes from the Illinois State Board of Education and Northern Illinois University's Illinois Interactive Report Card.
Each number represents the percentage of students whose performance met or exceeded the Illinois State Learning Standards on standardized tests. Those are the percentages used to measure whether a school district is making Adequate Yearly Progress under the law.