In this unit, students arrange objects in rectangular arrays. They will use the arrays for skip counting, repeated addition, and equal partitioning, in order to build foundations for multiplication in third grade. This unit will extend students’ prior knowledge of counting within 1000 and skip counting by 5s, 10s and 100s. Students may struggle to organize a set of objects into equal groups, particularly when having to partition a rectangle into samesized squares.
Unitataglance
Key concept: A group of objects can be organized in an array and thought of as a number of equal groups. 
Key concept: Skipcounting or repeated addition can be used to find the total number of objects in an array because there is the same number of objects in every row or column. 
Key concept: A rectangle can be partitioned into rows and columns of samesized squares. 


Suggested pacing 
Days 13 
Days 48 
Days 912 
Suggested class plan 



Additional unit information
Prior Knowledge Needed:
 Work with addition and subtraction; (Grade 1, Unit 13, 1.OA.7)
 Add and subtract within 20; (Grade 1, Unit 2, 1.OA.C)
 Circles and rectangles can be partitioned into two smaller equal shares (Grade 1, Unit 17, 1.G.A.3)
 When representing arrays with rows of 2 or 5, students may add to find the total and naturally point out a connection to skipcounting by twos or fives; (Grade 2, Unit 8, 2.NBT.2)
Units on the Horizon:
 Exploring equal groups as a foundation for multiplication and division (Grade 3, Unit 1. 3.OA.1, 3.OA.2)
 Developing conceptual understanding of area; (Grade 3, Unit 2, 3.OA.5, 3.MD.7)
Lessons, practice, & assessment