In This Unit of Study…

Students will explore equal groups to determine if a number is even or odd. Students will use rectangular arrays to work with repeated addition.  Students explore this concept by using concrete models (counters, square tiles, and linking cubes) and by creating pictorial representations on grid paper. Based on the commutative property of addition (explored in first grade), students can add either the rows or the columns to find the total amount within an array.  Students express the array by using equations.  Arrays at this grade level are composed of up to 5 rows and up to 5 columns.  This concept is a building block towards multiplication.

B.E.S.T. Benchmarks:

• MA.2.NSO.2.1 Recall addition facts with sums to 20 and related subtraction facts with automaticity. (Recall/Fluency 2.NSO.2.1 Video)
• MA.2.AR.3.1 Represent an even number using two equal groups or two equal addends. Represent an odd number using two equal groups with one left over or two equal addends plus 1.
• MA.2.AR.3.2 Use repeated addition to find the total number of objects in a collection of equal groups. Represent the total number of objects using rectangular arrays and equations

Overarching Key Concepts:

• Fluency: Solve addition and subtraction facts using ‘count on and count back’ strategies to build fluency to 20
• Identify odd and even numbers within 24
• Relate rectangular arrays to repeated addition