This Fluency Activity is a part of the Lesson 8, Unit 4, Grade 1. Say a series of four numbers, but replace one of the numbers with the word beep (e.g., 1, 2, 3, beep). When signaled, students say the number that was replaced by the word beep in the sequence. Scaffold number sequences, beginning with easy sequences and moving to more complex ones. Choose sequences that count forward and backward by ones and tens within 40.