Math Fact Strategies

Addition Strategies

Count on - (Best to use when adding 1, 2, 3, 4 or 5 but can be used with any)  

      Start at the larger number and count forward the smaller number.  

      Ex  8 + 4  start at 8, count forward 4  -  9, 10, 11, 12         8 + 4 = 12

Adding zero and ten 

        Adding zero is a no brainer. When adding 10 to a number just put a 1 in the tens place or in front of the number you’re adding it to.

Doubles - both addends are the same (these just need to be memorized)

       1 + 1     2 + 2      3 + 3     4 + 4     5 + 5      6 + 6      7 + 7     8 + 8     9 + 9    10 + 10

Doubles plus 1 **these are difficult **student must have a strong knowledge of doubles facts

     When one addend is just one more than the other, student recalls the answer for the doubles fact of the lesser addend and adds one more to it.  EXAMPLE  if 5 + 5 = 10 then 5 + 6  is 5 + 5 plus one more, so it's 11

Make a 10- (Best when adding with 8 or 9)     
Think “How many more are needed to make 10?” and then “How many are left over?” For example: 8 + 7 Think- How many more are needed to make 10?....2 If the 2 is taken from the 7, how many are left over?...5 So, 8 + 7 is 10 + 5, or 15. ***Knowing the different ways to make the number 10 (or 10 number bonds) is KEY to using the make a 10 strategy. You can go here to play a fun 10 number bond game.

Subtraction Strategies

Count back - (best when subtracting 1, 2, 3, 4 or 5 but can be used with any) 

        Start at the larger number and count backwards the smaller number. Example 8 - 3  Start at 8 - count back 3 -  7, 6, 5

 Count up- (best when subtracting a number that is close to the whole, like 16-14)

          Start with the lower number and count up to the whole. So for 16-14, start with 14 and count 15, 16. Since I counted 2 numbers, I know the difference is 2. 

Related doubles fact - This one relies on a strong knowledge of doubles facts.  

          If 5 + 5 = 10   then  10 - 5 = 5

Related addition facts - Some students can memorize the numbers in a “fact family” and use    

        it to help them solve subtraction problems. 

      Example - If a student knows that 3, 4 and 7 make a “fact family”  Then they can think

               that if 3 + 4 = 7 then 7 - 3 = 4 or  7 - 4 = 3.  We learned a lot about fact families at the 

               beginning of the year.  

Its common for students to confuse the next two ....

Subtracting all - When the numbers are the same you are left with zero.  

          9 - 9 = 0,   3 - 3 = 0 etc.  

Subtracting none or zero - When you subtract nothing you’re left with what you started with

           7 - 0 = 7        6 - 0 = 6