The focus of this lesson is selecting and using mental strategies to solve spoken word problems.  2.OA.A.1 focuses on solving one- and two-step word problems using addition and/or subtraction within 100, in a variety of situations, using drawings and/or equations; the teacher breaks down this meaty standard, focusing on the component of understanding and solving a one-step comparing problem by choosing a correct operation and strategy to solve the given word problem

The students choose their own mental strategies to solve the given word problems, rather than having a strategy prescribed for them.  Students are not learning any new math content in this lesson; instead, they are required to draw upon their prior knowledge and relate learned strategies to new situations. 

These 2nd graders apply previously learned computation strategies to solve comparing word problems within 100.  The lesson intentionally requires students to apply computation skills and strategies to unfamiliar problem situations.

In this part of the lesson, three students share different thinking strategies to solve the same spoken word problem: splitting, using a number line, and using base-ten blocks.  These students explain and chart their thinking for the group to strengthen all students' understanding of the solution methods, while the teacher questions and clarifies when necessary.

After the teacher poses a problem situation, students have time to think about an answer, and then they share their thinking with a partner.  All students participate in the partner-sharing, so it is clear that this is part of the classroom culture.  Although hard to discern, students can be heard saying: "First I..." "Then I..." to fully explain their thinking.