Standard: 1.OA.C6 – Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
Grade level: Grade 1
Subject: Mathematics
Domain: Operations & Algebraic Thinking
Teacher Overview
This standard focuses on developing fluency in addition and subtraction within 20, with a particular emphasis on strategies for addition and subtraction within 10. Mastery of these skills is critical for students as they lay the foundation for more advanced mathematical concepts. By using various strategies, students can develop a deeper understanding of number relationships and arithmetic operations. Before tackling this standard, students should be familiar with counting to 20, recognizing numbers, and basic addition and subtraction. They should also understand the concepts of ‘more than’ and ‘less than’.
After mastering this standard, students will be prepared to tackle more complex addition and subtraction problems, understand place value, and begin exploring multiplication and division.
Common Misconception 1
One common misconception is that addition always makes numbers bigger and subtraction always makes numbers smaller. This is incorrect because when dealing with zero or negative numbers, these operations can produce different results.
Intervention 1
To address this misconception, use number lines and manipulatives to show that addition and subtraction are related operations. Demonstrate how you can use addition to check subtraction and vice versa.
Common Misconception 2
Another common misconception is that the order of numbers in subtraction does not matter. Students may think that 5 – 3 is the same as 3 – 5, which is incorrect.
Intervention 2
Provide concrete examples and visual aids, such as number lines and counters, to show why the order of numbers in subtraction is important. Practice with real-world scenarios where the order of numbers affects the outcome.
Prerequisite Knowledge
Students should be able to count to 20, recognize numbers, and understand basic addition and subtraction concepts.
Subsequent Knowledge
Students will develop the ability to solve more complex addition and subtraction problems, understand the concept of place value, and begin to explore multiplication and division.
Instructional Activities
- Use number lines to practice addition and subtraction.
- Play counting games with objects.
- Solve simple word problems involving addition and subtraction.
- Use manipulatives like blocks or counters to visualize problems.
- Create and solve puzzles that involve making ten.
