Content Area: Math

 

Index: 4.3D Grade 2 CPI 1

 

Standard: 4.3 - Patterns and Algebra

 

Strand: D - Procedures

 

Cumulative Progress Indicator: 1 -  The student will understand and apply (but don’t name) the following properties of addition:

·        Commutative (e.g., 5 + 3 = 3 + 5)

·        Zero as the identity element (e.g., 7 + 0 = 7)

·        Associative (e.g., 7 + 3 + 2 can be found by first adding either 7 + 3 or 3 + 2)

 

Grade: 2

 

Sample Activities:

 

·        Students are given five computational problems to solve. They are permitted to use the calculator on only two of them. Two of the problems are related to another two by operation properties (e.g., 3 + 2 and 4 + 6 are related to 2 + 3 and 6 + 4 by the commutative property) and the last involves a property of number such as adding 0. Students share their thought processes in a follow up discussion.

 

·        The second grade teacher has a box containing slips of paper with open sentences such as 25 - 8 = ____  or 15 + _____  = 23. Students draw out a slip and tell or write a story which would involve a situation modeled by the sentence.

 

·        Students discover that, since the order of the numbers when adding them is not important, they can solve a problem like 3 + 8 by starting with 8 and counting up 3, as well as by starting with 3 and counting up 8.

 

·        In their math journals, students write their reactions to the following situation: Sally just used her calculator to find out that 324 + 486 was equal to 810. In another problem, she must find the answer to 486 + 324. What should she do? Why?