Assessment is most effective when it functions as a dynamic practice that permeates every layer of teaching. In this chapter, assessment appears as evidence in action, a source of conversation where daily indicators point the way with precision. A child&s;s pause while decoding, a margin note that reframes an idea, or a multilingual learner&s;s use of multiple languages to make meaning each opens a window to growth. Research-based practices show how formative routines sharpen instruction, how feedback accelerates mastery, and how qualitative indicators reveal the depth of thinking. Case studies and grade band notes highlight how teachers use these signals to refine instruction in the moment. Growth surfaces first in small moments of stamina, confidence, and strategic risk-taking before it registers in long-term measures. When students chart their own growth, data shifts from abstraction to personal agency. The chapter concludes by positioning assessment as both mirror and catalyst: a practice that strengthens instruction, affirms equity, and illuminates the path toward resilient literacy.