All of the math assessments in my Common Core Second Grade Math Packet have been tested with real students in four classrooms for four years. By using teacher and student feedback, I have revised these assessments to make them better.
I have read many math instruction books like Teaching Student-Centered Mathematics: Developmentally Appropriate Instruction for Grades Pre-K-2 by John Van de Walle, LouAnn Lovin, Karen Karp, and Jennifer Bay-Williams, Math Exchanges: Guiding Young Mathematicians in Small Group Meetings by Kassia Omohundro Wedekind, and Math Work Stations: Independent Learning You Can Count On, K-2 by Debbie Diller. These books have been instrumental in my teaching and curriculum development.