If a "curriculum" -- a set of instructional materials intended as a comprehensive course of study for a particular subject and grade level -- is well-aligned with state standards, it can help teachers deliver instruction that leads to students' mastery of those standards. However, most research suggests that curricula, in themselves, are not likely to change teachers' instruction because teachers use curricula in a variety of ways. Teachers likely need considerable supports to use curricula in ways that improve student learning. New results from the RAND American Instructional Resources Survey (AIRS), which was fielded to a national sample of public teachers and school leaders in spring 2019, shed light on how teachers use instructional materials in their classroom. AIRS specifically focused on the curriculum and other instructional materials used by kindergarten through 12th grade teachers in English language arts, mathematics, and science, along with how teachers are supported to use curriculum and the extent to which their students are engaged in standards-aligned classroom practices. The findings reveal the variety of ways in which teachers used curricula, as well as how curriculum use and supports varied among teachers in states and schools with different poverty levels. Analyses suggest that adoption of standards-aligned curricula -- in itself -- will not necessarily lead to more student engagement in standards-aligned classroom practices. Teachers who reported receiving more evaluative feedback and helpful professional learning (PL) on curriculum reported engagement in more standards-aligned classroom practices among all or nearly all of their students.