Maryland Math 1.NOS.E.10.d
The Standard
- 1.NOS.E.10
- Add within 100 including adding a two-digit number and a one-digit number and adding a two-digit number and a multiple of 10. Understand that when adding two-digit numbers, tens are added to tens, ones are added to ones, and sometimes it is necessary to compose or decompose a ten.
Represent and explain the calculation by connecting the strategy used to the meaning of addition.
Maryland College and Career Ready Standards for Mathematics (2025) · USE PLACE VALUE UNDERSTANDING AND PROPERTIES TO ADD AND SUBTRACT.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students show how they add two groups with counters, drawings, or an equation. They explain how each step combines the groups without losing or adding any objects.
What Mastery Looks Like
- For 8 + 5, a student can take 2 from the group of 5 to make 10, then add the remaining 3 to get 13. They can show where the 2 and 3 came from in their drawing.
Common Misconceptions
- Some students take 2 from the 5 to make 10, then add all 5 again. Others say they made 10 but cannot show which group the extra counters came from.
How to Assess It
- Ask students to show 9 + 4 with a ten-frame or drawing. Have them write an equation and explain where the 1 and 3 came from.
Lesson moves
Ways to Teach It
Give pairs 8 red and 5 blue counters; have them fill a ten-frame and explain why 3 counters remain.
Ask, 'Why does 8 + 2 + 3 show the same total as 8 + 5?' Have partners explain with a drawing.
Play Make Ten Match: students draw two number cards, build the sum with counters, and explain how they combined the groups.
Put 8 pencils in one cup and 5 in another; ask students to find the total and show each pencil in their equation.
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Printable 1.NOS.E.10.d Worksheet
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Related Standards
- 1.NOS.E.12.c
Represent and explain the calculation by connecting the strategy used to the meaning of subtraction.
- 1.NOS.C.7
Apply the Commutative Property of Addition and Associative Property of Addition as a strategy to add.
- 2.NOS.C.9.d
Represent and explain the calculation by connecting the strategy used to the meaning of addition and subtraction.
- 1.NOS.E.13.c
Represent and explain the calculation by connecting the strategy used to the meaning of subtraction.
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