In previous lessons, students added teen numbers and one-digit numbers. Students also added two-digit numbers and multiples of 10 and two-digit numbers and one-digit numbers without composing a ten. In this lesson, students are invited to add 2 two-digit numbers that are not multiples of 10 in a way that makes sense to them. Some students may attempt to write equations, but are not required to do so. The teacher draws diagrams and writes equations that match student thinking during the Activity Synthesis. Throughout the lesson, students explain their own methods, interpret others' methods, and connect different methods (MP3). Students notice different ways to make use of the base-ten system to count on or add by place (MP7).

What connections did students make between the different methods shared? What questions did you ask to help make the connections more visible?