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Mrs. Bagwell's First Grade Class
Teacher of the Year 2002-2003

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Angela Bagwell > Math Strategies for First Grade

Math Strategies for First Grade

 

Here are some important math strategies students can use when learning new math skills:

 


+1 Facts:

Count up one to find the answer (the sum).


Example: if the problem is 7 + 1, then count up once more form 7 (7, 8).

Using a number line or a ruler to count up one provides hands-on and visual support of this concept.


-1 Facts:

Count back one to find the answer (the difference).


Example: if the problem is 7 - 1, then count back once more form 7 (7, 6).

Using a number line or a ruler to count back one provides hands-on and visual support of this concept



+0 Facts:

Zero has no effect.  The answer (the sum) will be the addend that is not zero.


Example: if the problem is 5+0, the answer is 5.


-0 Facts:

Zero has no effect.  The answer (the difference) will be the addend that is not zero.


Example: if the problem is 5-0, the answer is 5.


Adding Doubles:

Use the double rap song:

0 plus 0 equals 0, Oh!

1 plus 1 equals 1, Eew!

2 plus 2 equals 4, More!

3 plus 3 equals 6, Kicks!

4 plus 4 equals 8, That’s Great!

5 plus 5 equals 10, Again!

6 plus 6 equals 12, Dig and Delve!

7 plus 7 equals 14, Let’s Learn!

8 plus 8 equals 16, You’re Keen!

9 plus 9 equals 18, Jelly Bean!

10 plus 10 equals 20, That’s Plenty!


We use matching towers of cubes to support this concept development in class.  Two rows or columns of blocks or pennies at home will provide hands-on support while practicing at home.


Subtracting a Number From itself:

The answer (the difference) is always zero when a number is subtracted from itself.

Example: if the problem is 8-8, the answer is 0.


Adding 2:

Lots of practice counting by 2’s will help student master this strategy. 


Look for items in everyday life that comes in 2’s: shoes, socks, mittens, gloves, ears, hand, feet, and eyes!


The odd and even rhymes come in handy:

Even Numbers: 0, 2, 4, 6, 8--Even numbers are really great!

Odd Numbers: 1, 3, 5, 7, 9—Odd numbers are just fine!


It is also helpful to label the number line an AB pattern.  The students will see that adding or subtracting 2 to a number that is labeled “A” will always result in an answer that is labeled “A”.  The same is true for adding or subtracting 2 to a number that is labeled “B”.


Example: if the problem is 7+2, remember that 9 is next after 7 in the skip counting pattern (AB) for odd numbers. If the problem is 4+2, remember that 6 in next after 4 in the skip counting pattern (AB) for even numbers.


While student are learning the skip counting patterns, I encourage them to recognize a plus 2 problem, look at the larger addend and say it, whisper the next number when counting up by 1’s, and then say the answer.


Example: 4+2 is a plus 2 problem.  Say “4”, whisper “5”, and then say the answer, “6”.


Another helpful practice tool is to write the numbers in a number line form 0-30.  Circle the odds with one color of crayon and circle the evens with another color of crayon.


Subtracting 2:

Lots of practice counting backwards by 2’s will help student master this strategy. 


Use items that normally come in 2’s will also help reinforce this concept---wouldn’t it be fun to do -2 problems with pairs of chopsticks?!


It is also helpful to label the number line an AB pattern.  The students will see that adding or subtracting 2 to a number that is labeled “A” will always result in an answer that is labeled “A”.  The same is true for adding or subtracting 2 to a number that is labeled “B”.


Example: if the problem is 9-2, remember that 7 is before 9 in the skip counting pattern (AB) for odd numbers. If the problem is 6-2, remember that 4 is before 6 in the skip counting pattern (AB) for even numbers.


While student are learning these patterns, I encourage them to recognize a minus 2 problem, look at the larger number and say it, whisper the next number when counting back by 1’s, and then say the answer.


Example: 7-2 is a minus 2 problem.  Say “7”, whisper “6”, and then say the answer, “5”.


Another helpful practice tool is to write the numbers in a number line form 0-30.  Circle the odds with one color of crayon and circle the evens with another color of crayon.


Doubles plus 1:

This strategy is used when adding 2 numbers that are counting buddies.  Note that the doubles strategy must be mastered before this concept is introduced. 


Example: 4+5 is solved in the following manner: 

4 and 5 are counting buddies because they are next to each other on the number line.

First, find the smallest addend. (4 is smaller than 5)

Next, double the smallest addend. (4 plus 4 equals 8, That’s Great!)

Last, add one to the doubles total to find the sum. (8 and 1 more is 9)

We use matching towers of cubes, and then add 1 more cube of a different color, to support this concept development in class.


Subtracting Half a Double:

Subtracting half a double means recognizing that the subtraction problem is the reciprocal of a double fact.  Hint: The magic triangle and knowledge of fact families helps to understand this concept.


Example:

6 + 6 = 12 is a doubles fact.

Subtracting half a double would be 12 – 6 = 6

The students needs to look at a problem such as 12 – 6 and realize that it is “half of a double”.

The answer is “the other half”, or “6”


Miscellaneous Facts:

There are the “leftovers”—facts that don’t fit into any of the above categories.  It is helpful to relate the fact to the nearest “make a 10” fact. 

Example:

7 + 4

Recognize that 7 + 3 equals 10

Recognize that 4 is 1 more than 3, so 7 + 4 must be 1 more than 10.

7 + 4 = 11


Using the magic triangle will help your child master the reciprocal subtraction facts.

Example: 11 – 4 = 7 and 11 – 7 = 4 are the subtraction facts related to the above example.

 

 

(Thank you to Mrs. Zider’s First Grade web site for these strategies!)