An important professional tool
A common, coherent, grade-by grade curriculum core is an important professional tool. When such a curriculum is neither vague nor overly prescriptive, it is a vital way to enhance teaching and learning. Such a curriculum allows teachers and parents to get a good sense of what students are expected to know and be able to do at any specific grade level. It helps teachers to identify which students are having difficulty and need extra help. It means that teachers can share best practices with their colleagues, that transient students won't suffer from a new curriculum every time they switch schools, and that all students are exposed systematically to the knowledge and skills they need, without risking unproductive repetition or lack of exposure to key topics. Further, if tests are not pegged to a broad curriculum, they will lead to a narrow, "teach-to-the-test" curriculum, which hurts kids and diminishes teaching.

Builds background knowledge
Research tells us that as students advance through the grades, their reading comprehension depends more and more on "background knowledge." A common core curriculum can help ensure that all kids are exposed to the rich, broad knowledge that can propel them past the notorious fourth-grade reading slump—and enable them to enter middle school ready to comprehend challenging materials. A knowledge-rich curriculum is especially vital for children from low-income families who, on average, have been exposed to roughly 30 million fewer words than children from professional families—and whose "word and world knowledge" is therefore so much less substantial than that of their peers.

Incorporates content into early reading blocks
We can't allow the important focus on early reading skills to crowd out the knowledge children need. With early literacy blocks often taking up two or more hours a day, it's important to bring content reading and discussions into those periods.

High-quality professional development
Research strongly suggests that when professional development is pegged to the curriculum being taught (instead of toward generic skills), it is more effective—and the effects are seen in student achievement. Plus, a shared curriculum enables the best kind of professional development—collegial efforts to share best practices and to overcome common teaching challenges.