This Fluency Activity is a part of the Lesson 20, Unit 4, Grade 1. This fluency activity allows students to practice their counting sequences as well as practicing mentally adding 10 and subtracting 10 from a given number. 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.