Dr. David Costello is an author and professional learning facilitator who focuses on mathematics instruction and learning. A classroom teacher and administrator based in Prince Edward Island, David has supported teachers in many roles including as a numeracy interventionist, numeracy coach, numeracy leader, and curriculum consultant. A popular speaker at conferences, David has also instructed numerous university courses on curriculum, differentiation, mathematics, and literacy. David is committed to transforming math instruction and creating more meaningful learning experiences for teachers and students.