If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.
You already know Dokkio is an AI-powered assistant to organize & manage your digital files & messages. Very soon, Dokkio will support Outlook as well as One Drive. Check it out today!

2-N-2-5

Page history last edited by Tashe Harris 6 years, 2 months ago

2.N.2.5 Solve real-world and mathematical addition and subtraction problems involving whole numbers up to 2 digits.

In a Nutshell

Students will develop understanding of solving addition and subtraction problems in real-world situations, using whole numbers up to 2 digits. In third grade, students will use a variety of strategies, including the relationship between addition and subtraction, the use of technology, and the context of the problem to assess the reasonableness of their answers.

Student Actions	Teacher Actions
Develop strategies for solving real-world addition and subtraction of two digit numbers using multiple representations (e.g., verbal, physical, symbolic, pictures, number line). Develop a deep and flexible conceptual understanding of real-world problems involving adding and subtracting two digit numbers through learning a variety of strategies (e.g., counting on, making tens, decomposing numbers, using base-ten blocks). Develop mathematical reasoning by exploring, comparing, and communicating a variety of addition and subtraction strategies of solving real world problems.	Use and connect among various representations and strategies of adding and subtracting two digit number real-world problems. Elicit and use evidence of student thinking of adding and subtracting real world problems to assess progress toward understanding and to support and extend learning. Facilitate meaningful mathematical discourse among students to build shared understanding of adding and subtracting two digit numbers real world problems by analyzing and comparing approaches and arguments.
Key Understandings	Misconceptions
There are two types of real-world subtraction problems: (1) take-away (e.g., I have 28 cookies and my sister ate 12) and (2) comparison (e.g., how much taller is Maria compared to Sally).	The Standard Computational Algorithm (SCA, i.e., the method of putting one number on top of the other then adding or subtracting) is the most efficient for adding and subtracting. (Introducing the SCA too early could be detrimental to a student’s math development.) When using the SCA, the sum of all digits become the answer. For example, 35+27=512.