## Grade 1 Mathematics Module 1, Topic G

Following the mid-module assessment, Topic G focuses on students understanding the meaning of subtraction as it relates to addition. In Lesson 25, students solve add to with change unknown problems as they have in Topic C using addition, but now relate that work directly to the act of taking away (1.OA.4). The work of this lesson starts with students calling upon their knowledge from previous add to with change unknown problems, and then applying it in the context of subtraction, using the addend to subtract from the total, in order to find the missing addend or part (1.OA.1). In this opening lesson, students use objects to represent discreet counts, which serves as a bridge to the number path, used in Lessons 26 and 27. Number bonds will continue to serve as a bridge between prior learning and this new learning. In these concluding lessons, students use the number path as pictured to the right, in order to find one part, count on to the total, and determine the number of counts it took to get to that total from the part (1.OA.5). The teacher engages students in deep discussion about these strategies as they relate to the contextualized situations of story problems, ensuring that students build a solid conceptual understanding of why and how one utilizes counting on to solve subtraction.