Several research summaries over the last few years have brought attention to the impact that high-quality instructional materials have on student learning. The U.S. Department of Education's What Works Clearinghouse, which produces summaries of rigorous research, has identified a number of effective curricula with large effect sizes on students' reading, math, and science learning. Summaries of rigorous research, have identified a number of effective curricula with large effect sizes on students' reading, math, and science learning. In fact, studies show that selecting a high-quality curriculum can have a bigger impact than a number of other popular interventions such as decreasing class size and offering merit pay to teachers. Surprisingly, effective curricula cost, on average, no more than weak curricula. When it comes to math curricula in the early grades, there is little relationship between cost and quality of instructional products. Among the less-expensive curricula are those made available online in an open educational resources format. In this instance, the basic curriculum is available for free downloading, with the costs restricted to printing and, in some cases, to supplemental material. Despite research evaluating effective curriculum solutions, individual teachers still self-select many of their instructional materials, and, as a result, most students are taught -- at least in part -- through idiosyncratic curricula that are not defined by school districts or states. The issue with such a program is that when teachers create their own lessons too much of the time, students may not get the benefits of a fully sequenced, coherent learning experience. Schools of education across the United States do not prepare future teachers for the many skills required to become effective curricula designers. Teachers and their students deserve access to effective, high-quality curriculum materials, rather than asking teachers to cobble together lessons largely without any professional training or support. National leadership organizations such as Chiefs for Change (2017, 2018) are now on the record as advocating for the shift to strong curricula. And more reports and respected education publications bringing attention to best practices (e.g. The Aspen Institute, 2018; Instruction Partners, 2017) are being seen. All of these efforts point to a simple but powerful message: Curriculum quality matters.