Students will be exploring a different problem type: part whole with addends unknown. This situation will demonstrate the part whole relationship in connection with addition and subtraction.

This lesson builds off the Day 4 math talk. Students will start to exploring the relationship between addition and subtraction through missing addend questions. The students will engage in a math talk, investigate a new task and a game or small group activity. 

This lesson will serve to develop a deeper understanding of the following big ideas:

• Addition names the whole in terms of the parts: when the parts of a set are known we call it addition 
• The part whole relationship is connected to addition as numbers are composed of two or more parts
• Addition can be used in action (or active) situations (i.e.: joining and separating) and static (or passive) situations (i.e.: part part whole) 
• Different addition situations will elicit different strategies 
• Number relationships provide the foundation for strategies to help students remember basic facts
• Student estimation of small amounts and understanding of quantity as the amount of objects
• Using the part whole model to understand the unknown parts of a problem. The unknown identified which operation needs to be used to solve the problem
• Provide students an opportunity to visualize a situation then interpret which operation is needed to  solve word problems 
• Models can be used to connect concrete to abstract 
• Explore addition strategies and provide opportunities for students to move from “direct modelling and counting all” to using counting on as a strategy to solve an addition question. Counting on is an important development as students work with bigger numbers, so they don’t have to model both numbers in the question