Formative assessment, the ongoing evaluation of student understanding during instruction rather than solely at its conclusion, has been described in the literature as one of the most consistently effective levers available to teachers for improving student learning. This paper reviews recent literature on formative assessment and feedback practices in the classroom, synthesizing evidence from meta-analyses and systematic reviews on their impact on achievement, motivation, and self-regulated learning. The review finds converging evidence that formative assessment, when paired with feedback that is timely, specific, and action-oriented, produces measurable gains in student achievement across educational levels, from K-12 reading instruction through graduate study. However, the literature also identifies substantial variation in effectiveness tied to feedback quality, teacher conceptions of assessment, and the degree to which feedback is actually used by students rather than ignored. Emerging research on generative AI as a tool for scaling formative feedback is noted as a promising but still early area of study. The paper concludes with implications for classroom practice, emphasizing the centrality of feedback quality and teacher professional development over the mere frequency of assessment activity, and identifies gaps in the evidence base warranting further research.