The purpose of this activity is for students to interpret and solve a story problem by adding or subtracting within 100. Students solve an Add To, Start Unknown problem, one of the more difficult problem types from grade 1. Students begin the activity by looking at the problem displayed, rather than in their books. At the end of the Launch, students open their books and work on the problem.
Monitor for students who use methods that show adding or subtracting by place to share in the Synthesis. Students who choose to use connecting cubes or base-ten blocks or who draw a diagram to represent the situation are using tools strategically (MP5). During the Synthesis, invite all students to explain why these methods work using their understanding of place value.
This activity uses MLR6 Three Reads. Advances: reading, listening, representing. Some students may benefit from continued use of MLR6 to support reading comprehension in Activity 2.