Teaching Tip Tuesday - Adding and Subtracting

Learning Expectations:

Grade 1 - Students are expected to understand the concept of adding and subtracting up to 20 using pictures or concrete representations (i.e. counters, number line). Memorization of addition and subtraction facts to 18 is not intended.

Grade 2 - Students are expected to use mental mathematics strategies to determine addition and subtraction facts to 18. (Mental strategies include: using doubles, making 10, one more/one less, two more/two less, building on a known double, addition for subtraction.)

Grade 3 - Students are expected to use mental mathematics strategies and number properties to recall basic addition and subtraction facts to 18. (Mental strategies are similar to Grade 2. Number properties include understanding the quality of zero and understanding that numbers added in a different order will still equal that same sum i.e. 4 + 8 = 8 + 4.)

Below is a practical order for teaching kids addition and subtraction facts:
1. Facts up to 10 adding 1 and subtracting 1
2. Facts up to 10 adding 2 and subtracting 2
3. Facts that equal 10(0+10, 1+9, 2+8, 3+7, 4+6, 5+5, 6+4, 7+3, 8+2, 9+1, 10+0)
4. All the facts up to 10 that haven't been covered(3+4, 3+5, 3+6, 4+3, 4+5, 5+4, 6+3)
5. Doubles (1+1, 2+2, 3+3, 4+4, 5+5, 6+6, 7+7, 8+8, 9+9, 10+10)

***Once the above facts are quite familiar with your child, she is ready to start using mental mathematics strategies to determine the facts to 18. Below are examples of how to use various mental mathematics strategies:

Grade 2 Strategies:- doubles (i.e. for 6+8, think 7+7)
- doubles plus one (i.e. for 6+7, think 6+6+1)
- doubles take away one (i.e. for 6+7, think 7+7-1)
- doubles plus two (i.e. for 6+8, think 6+6+2)
- doubles take away two (i.e. for 6+8, think 8+8-2)
- making 10 (i.e. for 7+5, think 7+3+2)
- building on a known double (i.e. 6+6=12, so 6+7=12+1=13)
- addition to subtraction (i.e. 11-6, think 6+?=11)

Grade 3 Strategies - same as Grade 2 strategies, as well as:
- commutative property (i.e. for 3+9, think 9+3)
- provide a rule for determining answers for adding and subtracting zero


Do you have multi link cubes? Multi link cubes are an excellent math manipulative that is ideal for "seeing" adding and subtracting and for making 10s. School Specialty Canada has packages of 100 available here: Multi link cubes





Peggy Kaye's Games for Math is always a hit with my own kids. It's "drill and practice" in disguise. Chapters Indigo has it available here: Games for Math