Standard: 1.NBT.B2 – Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
Grade level: Grade 1
Subject: Mathematics
Domain: Number & Operations in Base Ten
Teacher Overview
This standard focuses on helping students understand that in a two-digit number, the first digit represents tens and the second digit represents ones. This understanding is crucial as it lays the foundation for place value, which is a key concept in mathematics. Mastery of this standard will support students in performing operations with larger numbers and understanding the base-ten number system. Before tackling this standard, students should be comfortable counting to 100, recognizing and writing numbers up to 20, and understanding basic addition and subtraction concepts.
After mastering this standard, students will be able to perform addition and subtraction with two-digit numbers, including regrouping. They will also begin to explore place value in three-digit numbers, setting the stage for more advanced arithmetic.
Common Misconception 1
A common misconception is that the digits in a two-digit number are independent of each other. For example, a student might think that the digits in 23 are just ‘2’ and ‘3’ without understanding that ‘2’ represents two tens (20) and ‘3’ represents three ones (3).
Intervention 1
To address this, use place value charts and manipulatives like base-ten blocks to visually and physically represent the tens and ones. This helps students see the composition of the number.
Common Misconception 2
Another misconception is that the position of a digit does not affect its value. A student might think that 21 and 12 are the same because they contain the same digits.
Intervention 2
Engage students in activities that involve comparing and ordering numbers, and use number lines and place value charts to emphasize the importance of digit position.
Prerequisite Knowledge
Students should be able to count to 100, recognize and write numbers from 0 to 20, and understand basic addition and subtraction.
Subsequent Knowledge
Students will learn to perform more complex addition and subtraction with two-digit numbers, including regrouping (carrying and borrowing). They will also begin to explore place value concepts in three-digit numbers.
Instructional Activities
- Using place value blocks to construct and deconstruct two-digit numbers.
- Playing games that involve grouping objects into tens and ones.
- Solving puzzles that require matching numbers to their tens and ones representations.
- Creating place value charts with students and practicing with different numbers.
- Incorporating real-life examples, such as counting money or items in a store.
