CCA moved away from the TEKS for several reasons:
Although the TEKS theoretically covers all the levels of standard expectations of critical thinking (Bloom’s Taxonomy of Learning Domains), it is still deficient in the high rigors or critical thinking required at Cornerstone. We feel like the CCSS is more conducive to teaching critical thinking and sets that thinking in a strong literacy context.
Since the Common Core does not prescribe any pedagogical method in particular or conceptual content mandates in general, it is less vulnerable to the insertion of liberal or non-Christian worldview perspectives.
The TEKS is overly oriented to content. One common criticism of the TEKS is that they cover such a breadth of topics that their depth is questionable. Moreover, even if an instructor spent only 15 minutes on any given objective, a lofty goal to say the least, it would take 23 years to teach these standards. The CCSS, while it focuses on content, it emphasizes depth of understanding and its application to thinking skills.
One of the strongest reasons for parting from the TEKS is that they mandate the teaching of material that is inconsistent with a Christian Worldview, and in some cases, especially in the areas of history and science, contradict a Christian Worldview.