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2-A-2-2

Page history last edited by Tashe Harris 6 years, 9 months ago

2.A.2.2 Generate real-world situations to represent number sentences and vice versa.


In a Nutshell

Second graders build on their previous work with operations by writing number sentences to represent a real world or mathematical situation involving addition and subtraction. In addition, they write a real world problem to represent a given number sentence. In later grades students will be asked to represent number sentences with real world situations using all operations.

Student Actions

Teacher Actions

  • Develop mathematical reasoning by justifying their solution strategies, explaining their thinking, questioning each other, and forming conjectures.

  • Develop a deep and flexible conceptual understanding of number sentences by using concrete materials to explore and describe number relationships expressed in open-ended number sentences.

  • Develop accurate and appropriate procedural fluency by writing a number story to match a given number sentence and writing a number sentence to match a given situation.

  • Facilitate meaningful mathematical discourse about students’ strategies for solving number sentences with unknowns.

  • Pose purposeful questions, keeping the focus on students’ understanding of numbers and the relationship between addition and subtraction.  Asking “Why? How do you know? Will that always be true? Explain your brain.”

  • Use and connect mathematical representations by facilitating students' use of concrete materials such as colored counters for accuracy and student understanding.

  • Implement tasks that promote reasoning and problem-solving of an unknown value in which the unknown is in different locations.

Key Understandings

Misconceptions

  • Number sentences involving addition, subtraction, and unknowns are used to represent given problem situations.

  • The equal sign means "the same as".

  • Number sentences can be created to match given story problems.

  • Story problems can be created to match given number sentences.

  • The only format for a problem is a + b = c or a - b = c, not recognizing that it can also be c = a + b or c = a - b.

  • n = 90 - 13 is read: 13 minus 90 equals n. Students need constant reminders to read left to right on either side of the equal sign.

  • Students ignore the presence of letters or unknowns in an equation.

  • An equal sign means "and the answer is." In this way, when they see an equal sign, they want to carry out the operation preceding it. They need to think of the equal sign as meaning "is the same as."


OKMath Framework Introduction

2nd Grade Introduction

2nd Grade Math Standards

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