What are the Big Ideas?
- Addition and subtraction are inverse operations
- Addition and subtraction have certain properties. For example, there is the commutative property of addition.
- Strategies for solving 1-and 2- digit addition and subtraction problems can be used to solve problems involving numbers with increasing digits.
How Will these Concepts Develop?
- Students use patterns to develop strategies for addition and subtraction of 1-digit numbers, including finding missing numbers.
- Students use Base Ten Blocks and place-value mats to add and subtract 1 and 2 digit numbers, and later to add and subtract 3-digit numbers.
- Students use mental math to add and subtract. They estimate sums and differences.
- Students develop proficiency with adding and subtracting 3-digit numbers using the standard algorithm.
Why are these concepts important?
The ability to recognize patterns assists students to recall basic facts proficiently. Fluency with computations involving the addition and subtraction of whole numbers is essential in the world around us. Students should have a good understanding of number and the meanings of and relationships between the operations of addition and subtraction. A solid foundation is necessary for learning and applying math to higher grades.
From: Math Makes Sense: OntarioTeacher Guide: Pearson Education Canada, 2004.