CCSS.Math.Content.2.OA.C.3
The standard
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 express an even number as a sum of two equal addends.
Common Core State Standards for Mathematics · Operations and Algebraic Thinking
What this standard means
Students need to decide if a set up to 20 is odd or even. They can do this by making pairs, counting by twos, or splitting the set into two equal groups. For even numbers, they also write an equation with two equal addends, such as 8 = 4 + 4.
Mastery looks like a student sorting numbers or objects as odd or even and explaining why. They should connect “no leftovers” with even and “one leftover” with odd. Common trouble spots are counting pairs incorrectly, thinking any two-addend equation works, or writing 10 = 6 + 4 instead of equal addends.
Ways to teach it
- Give each student 17 counters and have them pair them up, record odd or even, then repeat with three new numbers.
- Ask students to write: Is 14 odd or even, and how do your pairs or equal groups prove it?
- Show 12 dots on a card and ask students to write an equal-addends equation on a sticky note.
- Look at shoes in a classroom line and ask whether the total number of shoes will always be odd or even.
Plan a lesson for CCSS.Math.Content.2.OA.C.3
Generate a complete lesson plan aligned to this standard, with objectives, activities, and materials. Free, no account needed.
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