Barbara R. Blackburn, PhD, a top 30 Global Guru in Education, is the author of multiple books, including Rigor Is NOT a Four-Letter Word, Rigor and Assessment in the Classroom, Rigor and Differentiation in the Classroom, Rigor in the RTI and MTSS Classroom, and Rigor in Your School: A Toolkit for Leaders. She is an international speaker and regularly provides schools and districts with professional development.