Developing Essential Understanding of Addition and Subtraction for Teaching Math in PreK-Grade 2

What is the relationship between addition and subtraction? How do you know whether an algorithm will always work? Can you explain why order matters in subraction but not in addition or why it is false to assert that the sum of any two whole numbers is greater than either number?It is organised around two big ideas and supported by smaller, more specific, interconnected ideas (essential understandings). Gaining an understanding about addition and subtraction is essential as they are the foundation for students’ later learning of multiplication and division.Essential Understanding Series topics include:Number and Numeration for Grades Pre-K-2Addition and Subtraction for Grades Pre-K-2Geometry for Grades Pre-K-2Reasoning and Proof for Grades Pre-K-8Multiplication and Division for Grades 3-5Rational Numbers for Grades 3-5Algebraic Ideas and Readiness for Grades 3-5Geometric Shapes and Solids for Grades 3-5Ratio, Proportion and Proportionality for Grades 6-8Expressions and Equations for Grades 6-8Measurement for Grades 6-8Data Analysis and Statistics for Grades 6-8Function for Grades 9-12Geometric Relationships for Grades 9-12Reasoning and Proof for Grades 9-12Statistics for Grades 9-12