Dr. David Costello is an author and professional learning facilitator who focuses on mathematics instruction and learning. 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. Currently a vice-principal in Summerside, PEI, David is committed to creating more meaningful learning experiences.