In the 21st century, a deep understanding of mathematics, and the ability to apply that understanding, is more important than it has ever been. In Montgomery County (Maryland) Public Schools (MCPS), and across the country, mathematics instruction is changing to provide students with the skills and knowledge they need for success in college and the workplace. This booklet provides parents with some important information about why these changes are needed; how MCPS is improving mathematics instruction; what deep understanding means; and how MCPS is working to meet the needs of all students to ensure their success. [This document was published by the Department of Materials Management for the Office of Teaching, Learning and Programs.]