Content Area: Math

 

Index: 4.1B Grade 4 CPI 10

 

Standard: 4.1 - Number and Numerical Operations

 

Strand: B - Numerical Operations

 

Cumulative Progress Indicator: 10 -  The student will understand and use the inverse relationships between addition and subtraction and between multiplication and division.

 

Grade: 4

 

Sample Activities:

 

·        Students take 7x8 block rectangular grids printed on pieces of paper. They each cut along any one of the 7 block-long segments to produce two new rectangles, for example, a 7x6 and a 7x2 rectangle. They then discuss all of the different rectangle pairs they produced and how they are all related to the original one.

 

·        Students write a letter to a second grader explaining why 2+5 equals 5+2 to demonstrate their understanding of commutativity.

 

·        Students explore modular, or clock, addition as an operation that behaves differently from the addition they know how to do. For example: 6 hours after 10 o'clock in the morning is 4 o'clock in the afternoon, so 10 + 6 = 4 on a 12-hour clock. How is clock addition different from regular addition? How is it the same? How would modular subtraction and multiplication work?