This Fluency Activity is a part of the Lesson 10, Unit 2, Grade 2. This activity challenges students to mentally subtract the ones and add the difference to 10. Draw a number bond for the first example to support student answers. Students may answer verbally or on their personal white board. Students who are struggling with pictorial representations may need to use concrete models (e.g., linking cubes) to demonstrate conceptual understanding of addition and subtraction. Incremented bars can be added to the tape diagram as a transition from base ten blocks to a pictorial model, as well.