Standard

Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).

Student Language:

• "I can understand how counting up is like adding and counting down is like subtracting."

Explanation

About the Math, Learning Targets, and Rigor

This standard asks for students to make a connection between counting and adding and subtraction. Students use various counting strategies, including counting all and counting on with numbers up to 20. The counting and counting back strategies occur when students are able to hold the “start number” in their head and count on from that number. When students count on for subtraction (3) from 7, they should connect this to 7 − 3 = 4. Students write 7 − 3 =? and think I count on 3 + ? = 7.

Have students invent and refine their strategies for solving problems involving sums and differences less than or equal to 20 using the numbers 0 to 20. Ask them to explain and compare their strategies as a class. Provide multiple and varied experiences that will help students develop a strong sense of numbers based on comprehension – not rules and procedures.

Ask students to verbally explain how counting on helps to add one part to another part to find a sum. Discourage students from inventing a counting back strategy for subtraction because it is difficult and leads to errors.

Resources

Videos

• Khan Academy
  • Scroll to 1.OA.3, click on skill, find videos on left side of each skill

Extra Practice

• North Carolina Tasks
• Illustrative Math Tasks
• Howard County Tasks
  • Click on 1st grade at bottom, then 1.OA.3
• Common Core Sheets