# PS 42X Grade 1 Unpacking Chapter 4

### Grade 1: Chapter 4 Subtraction Strategies

Thoughts on chapter:

1. Tools: Ten-frame, number path/strip, number grid, number bead strings, counters
2. Models: Number line,
3. Strategies: Count back, Count on from subtrahend until you reach the minuend, decompose the subtrahend
4. Stage 3 Fluencies: problem solving, using tools and models to solve subtraction problems involving a subtrahend of 2 or greater
5. Stage 4 Fluencies: ways to make 10, taking away 0 and 1,
6. Lesson 4.1: Focus on specific concepts to build Stage 4 fluency.  Separate lessons in practice of concepts/skills/Stage 4 fluencies and problem solving times.
7. Lesson 4.2 & 4.3: Combine theses lessons, but do over 2 or 3 days. Kinds think additively at this point in their development, so use it to your advantage. Model these ideas concretely. Ensure that students are reasoning through the problems. Make sure that they can explain what is happening and why.
8. Lesson 4.3: Look at the Advanced Learners, pg. 224. Make this into a “Find Someone Who”.
9. Lesson 4.4: Connect to 4.5 from the very beginning. Emphasis the point the it does not matter where I take a certain amount from when looking at concrete representations, but it is a matter of organizing our thoughts when we begin take from ten.  Use the idea that 12 – 8 can be solved by 10 – 8, which is 2, but I still have the 2 more that were in the second ten-frame, so 12 – 8 is 4.
10. Lesson 4.5: Do not show examples in the book! Act out instead, then record on anchor chart. The focus is development flexibility with numbers and building number sense. You want to hear a students reasoning out loud.
11. Lesson 4.6: Weave in this lesson throughout the unit of study. Do not do separately.
12. Kagan Structures: Find Someone Who, Showdown, Rally Coach
13. Key Things to Remember:
• Always provide a context!
• Use manipulatives and tools!