Changing order or grouping does not change a sum

Skill, addition, level 1

Lines up with: 1.OA.B.3

Builds on

• Add and subtract within 10
• Putting two things together weighs the same in either order

Leads to

• Add and subtract fractions with the same denominator, including mixed numbers
• Add and subtract within 20 using strategies

Lessons

• Lesson 4: A + B = B + A · The fourth identity

All ideas