This lesson is optional because it is an opportunity for extra practice that not all classes may need. In Activity 1, students learn Stage 4 of the How Close? center. In this new stage, called How Close—Add to 1,000, students pick 8 digit cards and then choose 6 of them to make an expression that yields a number as close as possible to the target number, 1,000. In Activity 2, students learn Stage 8 of the Five in a Row: Addition and Subtraction center. In this new stage, students add within 1,000, with composing. Then they choose to continue working on Five in a Row: Addition and Subtraction, or choose between two previously introduced centers that focus on addition with three-digit numbers.