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Intentionality…

The purpose of the Day 2 activities is to reinforce key concepts from Day 1. Students will engage in a string of related problems through a math talk and will have an opportunity to complete purposeful practice. The math talk and purposeful practice serve to develop a deeper understanding of the following big ideas.

Some of the big ideas that may emerge today include:

• Understanding hierarchical inclusion allows for flexible composing and decomposing of numbers
• Numbers can be decomposed by separating a whole into two or more parts
• Subtraction names the missing part in terms of the whole
• Different subtraction situations will elicit different strategies 
• Number relationships provide the foundation for strategies to help students remember basic facts
• Addition and subtraction are related in that addition names the parts in the whole and subtraction uses the whole to find a missing part. 
• Subtraction can be used in either take away, comparison, or missing addend situations.
• Models can be used to connect concrete to abstract 

Before starting this unit, students should be familiar with:

• Facts of 10 ( e.g., 6+4 = 10, 10-4 = 6)
• Flexibility when decomposing numbers (e.g., 13 can be decomposed into 10 and 3, but also 9 and 4, 8 and 5, etc)
• The Down and Under Ten strategy which can be explored in the Fruit Picking Unit.