Students who require remedial instruction manifest a multitude of instructional needs. Paramount among them are sufficient response repetitions to acquire new content, ways to increase their relatively slow rates of learning, and opportunities to engage in activities that will enable them to maintain learned content. Teachers tasked to provide remedial instruction, such as those who present Tier 2/3 instruction in a multi-tier system of supports (MTSS), need interventions that can address these students’ instructional needs either singly or in combination. In particular, effective and efficient interventions are preferable. In this paper an evidence-based practice - systematic trial-based instruction - that can meet these needs is explained. It is an instructional approach that is predicated on student opportunities to respond but readily allows for embellishments that increase instructional efficiency by increasing students’ learning rates and permits them to maintain previously mastered content. This approach is first defined and explained in terms of its three core phases. Next, supporting evidence regarding this approach’s effectiveness is presented, as are examples of its use. These examples are followed by a discussion of a concept, called instructional density, that has emerged from this approach. The paper concludes with a discussion of reasons why teachers should consider using systematic trial-based instruction. Teachers will find it is a flexible approach that allows them to address the science and art of teaching.