NBT Mastery Scale Guide
Proficiency Scale
Mathematics: Numbers & Operations in Base Ten
2.NBT.B.5
Mastery Guide
Target Standard
"Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction."
4 Advanced
Exceeding Standard
Demonstrates mastery beyond grade level expectations.
- The student can fluently add/subtract within 1,000.
- The student can evaluate and justify strategy efficiency.
Work Example: \(523 - 288\)
Student uses compensation:
"(523 + 12) - (288 + 12) = 535 - 300 = 235."
"I added 12 to both to make a friendly 300. No regrouping needed!"
Target Mastery
3 Proficient
Meeting Standard
Consistent application of grade-level skills.
- The student can fluently add/subtract within 100.
- The student can accurately regroup tens and ones.
Work Example: \(62 - 38\)
Student uses an open number line:
Starts at 62. Jumps back 30 to 32. Jumps back 2 to 30. Jumps back 6 to 24.
"I broke 38 into 30, 2, and 6 to get to the next ten."
2 Developing
Approaching Standard
Grasps basics but needs support with complexity.
- The student can solve problems without regrouping.
- The student can represent problems with concrete models.
Work Example: \(45 + 23\)
Student uses base-ten drawings:
Draws 4 tens / 5 ones. Draws 2 tens / 3 ones. Counts total.
"4 tens plus 2 tens is 60. 5 ones plus 3 ones is 8. That's 68!"
1 Beginning
Novice Foundation
Building prerequisite skills for the standard.
- The student can solve fluently within 20.
- The student can identify tens/ones in 2-digit numbers.
Work Example: \(14 - 6\)
Student uses counting back:
Starts at 14. "13, 12, 11, 10, 9, 8."
"I used my fingers to count back 6 spots from 14."
Key Terminology
Fluency
Efficiency and flexibility in strategy choice.
Decomposing
Breaking numbers into place value parts.
Instructional Notes
Standard 2.NBT.B.5 Mastery Document • Final Review
NBT Mastery Check Worksheet
NBT Mastery Check
Assessment for Standard 2.NBT.B.5
Name:
Date:
Instructions for Students:
Complete each section to show your mathematical thinking. This assessment helps determine your current mastery level on the 2.NBT.B.5 Proficiency Scale.
1
Level 1: Beginning
\(14 - 6 = \)
\(9 + 7 = \)
Place Value Check:
Look at the number 85:
How many tens? _______
How many ones? _______
2
Level 2: Developing
Solve using base-ten drawings (no regrouping):
\(45 + 23 = \_\_\_\)
Solve using any strategy (no regrouping):
\(79 - 36 = \_\_\_\)
3
Level 3: Proficient (Target)
Solve showing your regrouping (composing a ten):
\(56 + 27 = \_\_\_\)
Use an Open Number Line to solve:
\(62 - 38 = \_\_\_\)
4
Level 4: Advanced
Solve within 1,000 using a place value strategy:
\(523 - 288 = \_\_\_\)
Strategy Evaluation Challenge
Look at this problem: \(99 + 45\).
Is it more efficient to use Counting On or Compensation (adjusting the numbers) to solve? Explain why your choice is faster or easier.
Teacher Mastery Placement
Level 1
Level 2
Level 3
Level 4
Placement Tool • CCSS 2.NBT.B.5 • Final Version
