CCSS.Math.Content.1.OA.C.5
The standard
Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).
Common Core State Standards for Mathematics · Operations and Algebraic Thinking
What this standard means
Students need to connect counting with adding and subtracting. They should see that adding 2 means counting on two numbers, and subtracting 3 means counting back three numbers. They are not just memorizing facts. They are using the number sequence to make sense of operations within 20.
Mastery looks like a student starting at the larger addend, counting on accurately, and saying the matching equation. For subtraction, they count back or count up to find the difference. Common trouble spots are starting at 1 every time, counting the starting number as a step, and losing track of how many counts were made.
Ways to teach it
- Hands-on activity: Give students number lines and counters, then have them model 8 plus 3 by starting at 8 and moving three jumps.
- Prompt: Ask, How is counting on from 9 to solve 9 plus 4 different from counting all the objects?
- Quick assessment: Show 12 minus 3 and ask students to count back aloud, then write the equation and answer.
- Real-world connection: Use a board game spinner and ask students to say their starting space, count on the move, and name the new space.
Plan a lesson for CCSS.Math.Content.1.OA.C.5
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