B. Reasoning from Known Facts
Use the facts that are given to help you complete the table.
- How does solving 10 − 8 help you solve 11 − 8?
- How does solving 10 − 8 help you solve 9 − 8?
Lesson 1
T-Shirt Factory Problems
Est. Class Sessions: 1Daily Practice and Problems
Teacher Notes
X
TIMS Task
Use this task to practice subtraction facts in Groups 3 and 4.
After students write their answers, let them discuss their strategies as well as their answers.
- 1
- 2–3.
- Answers will vary. Take time to highlight the various strategies that emerge as students discuss the completed table. Give students an opportunity to articulate how using the facts involving 10 were helpful. Possible response for Question 2: If 10 − 8 = 2, then 11 − 8 must be one more, or 3. Possible response for Question 3: If 10 − 8 = 2, then 9 − 8 will be one less, or 1.