Directions for using Double-Tens Frames for Subtraction Unit 8 N11: Model, represent and explain subtraction as take-away and comparison. Corrective Instruction: Use blank 20 frames and let students model the problem. They can record the number sentence once finished.
1. Introduce the Double-Tens frame. Ask: What do you notice about this? If needed, ask: How many squares on top? How many on the bottom? How many altogether? 2. Model numbers on the frame (Model “12” as 10 counters on top, 2 on the bottom). Ask: What do you see? If needed, ask: How many squares on top? How many on the bottom? How many altogether? Repeat this by modeling numbers in the range 11-20. Encourage students to use the structure of the frame rather than counting by ones. ie. Know “19 counters” because it is one less than 20 instead of counting all 19 counters; Know “17 counters” because it is 15 counters plus 2 more. Teachers can encourage this by asking questions like “is there a more efficient way to know that is 19?”. 3. Allow students to use counters to build a few numbers in the range 11-20. 4. Use the frame to model a subtraction story problem. For example, “James has 14 crayons. He gave Sara 5 crayons. How many crayons does he have left?” After solving, have students write a number sentence representing the problem. 5. Give students story problem cards. They should model the problems on the DoubleTens frames with counters. After solving each problem, they should write a number sentence representing the problem.