Declining national assessment scores and continuous critiques of Common Core curricula have presented persistent challenges for stakeholders within the American education system. This study was an investigation of the existence of parallelism in five commonly used Common Core middle school mathematics curricula. An embedded mixed methods research design including the Lawshe Method, was used to determine whether lessons were congruent in the way they represent the expectations in Common Core State Standards 6.G.A.1, 6.G.A.3, and 8.G.B.7. Ten panelists with experience using and/or supporting the Common Core standards, evaluated lessons in each of the five curricula using a standards-specific evaluation tool of student and teacher behaviors. The findings indicated that while the lessons aligned with the Common Core State Standards for Mathematics, they lacked parallelism and consistency when compared to each other. This investigation highlighted the critical need for educators involved in teaching and learning, curriculum development, curriculum evaluation, and assessment writing to operate in the same thread of understanding before using the standards to create learning experiences, materials, rankings, or assessments. Future research endeavors should continue to audit the knowledge of math educators, particularly those involved in creating models and materials for classroom use. Results from this study contribute to the gaps in educational research regarding the alignment of math instructional materials, math standards literacy, and inter-rater reliability in math standards-based instruction where educators consistently share the same understanding and evaluations of math concepts. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]