Relate repeated subtraction to division Unit of Study: 2 Global Concept Guide: 2 of 7

Content Development Approximately two days should be spent on developing an understanding of the relationship between repeated subtraction and division. Model multiplication and division in MA.3.A.1.1 refers to direct modeling. Direct Modeling is the use of manipulatives or drawings along with counting to represent directly the meaning of an operation or story problem. (Van de Walle 7 th ed., 214.)

Day 1  Provide students with word problems that encourage direct modeling of division: (Use the problems referenced in the GCG) Example:  Gene has some tomato plants. There are 6 tomatoes on each plant. Altogether there are 24 tomatoes. How many tomato plants does Gene have?  Students use the snap cubes (or other manipulatives) to make groups of 6 until they use all 24 cubes.  Then, they determine the number of tomato plants. 24 – 6 – 6 – 6 – 6 = 0

Day 2 12 ÷ 3  The focus of day two is on relating repeated subtraction to division through a linear model. By the end o f da By the end of day two:  Students use centimeter cubes (or other manipulatives) on a number line to represent the problem.  Student should be able to write and Justify an expression or equation.

Enrich/Reteach/Intervention  For students struggling with the concept, use the reteach activity on pg. 223b in the Ch. 5 Teachers Guide.