CCSS.Math.Content.2.OA.C

CCSS.Math.Content.2.OA.C is a cluster heading. These are the individual standards under it.

• CCSS.Math.Content.2.OA.C.3

  Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counting them by 2s; write an equation to expr...

• CCSS.Math.Content.2.OA.C.4

  Use addition to find the total number of objects arranged in rectangular arrays with up to 5 rows and up to 5 columns; write an equation to express the total as...

01

What Students Need to Do

Students arrange objects in equal groups and rectangular arrays. They find totals by skip-counting or adding equal addends. They also decide whether a number is odd or even by making pairs.

02

What Mastery Looks Like

Given up to 25 objects, students can build an array with no more than 5 rows or columns and write a matching addition equation. They can pair up numbers through 20 and explain that a leftover object means the number is odd.

03

Common Misconceptions

Students may make groups with different amounts but still call them equal. They may count rows instead of all objects or write addends that do not match the array. Some think every number can be paired with no object left over.

04

How to Assess It

Give students 15 counters. Ask them to make 3 equal rows, draw the array, write a repeated-addition equation, and use pairs to label 15 odd or even.

1. 01

   Give pairs 20 counters and number cards. Students build each amount into equal rows, then record a repeated-addition equation.

2. 02

   Ask, “How can pairs prove whether 13 is odd or even?” Students draw a model and explain the leftover or equal split.

3. 03

   Play Array Match with cards showing arrays, repeated-addition equations, and totals. Students collect sets of three that represent the same quantity.

4. 04

   Arrange 18 classroom items into equal trays, then compare possible tray counts and identify arrangements that leave leftovers.

• CCSS.Math.Content.3.OA.B.5

  Apply properties of operations as strategies to multiply and divide.

• CCSS.Math.Content.3.OA.A.3

  Use multiplication and division within 100 to solve word problems in situations involving equal groups, arrays, and measurement quantities, e.g., by using drawi...

• CCSS.Math.Content.3.OA.A

  Represent and solve problems involving multiplication and division.

• CCSS.Math.Content.4.OA.B

  Gain familiarity with factors and multiples.