This Fluency Activity is a part of the Lesson 18, Unit 2, Grade 1. This fluency activity strengthens the understanding of place value and prepares students to understand ten as a unit by the module's end. Show students numbers from 10 to 19 with Hide Zero cards (e.g., 15). Students say an addition sentence with 10 as an addend. As students say the sentence, break apart the Hide Zero cards to model the equation. Students can also say the numbers the Say Ten way and the regular way.