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Math Corner

Math Corner  

Follow this link to the district "Math Corner" page.  Here you will find teaching videos.

http://www.desotocountyschools.org/Default.asp?PN=Pages&SubP=Level2&DivisionID=%2710922%27&DepartmentID=%2711058%27&SubDepartmentID=%27%27&PageID=%2716039%27&SubPageID=%2714106%27

Rounding to nearest 10:

Determine what two "10's" the number would come between on a number line.  Determine which "10" the given # is closer to.  Look at digit in ones place - 1, 2, 3, 4 round down / 5, 6, 7, 8, 9 round up!

 

40  47 50          (41, 42, 43, 44 will round down to 40 - 45, 46, 47, 48, 49 will round up to 50)

 

730  732 740   (730, 731,732,733, 734 will round down to 730 - 735, 736, 737, 738, 739 will round up to 740)

 

 

 

 

 

Quadrilaterals:
  • Parallelograms - quadrilaterals with two sets of parallel lines { square, rectangle, rhombus }

 

  • Square:  parallelogram with four congruent (equal) sides, 4 RIGHT angles, 4 vertices
  • Rhombus:  parallelogram with four congruent sides, 4 angles, 4 vertices
  • Rectangle:  parallelogram with 4 RIGHT angles, 4 vertices, opposite sides are congruent (equal)

 

Trapezoid - quadrilateral with one set of parallel sides  (NOT a parallelogram) 

Word Problem Tips:

  

Steps to solving word problems:

 

1. Read the problem.  That's it, read it.

 

2. Underline the question.

 

3. Flip the question into a statement leaving a blank for the answer.  (WRITE THIS STATEMENT DOWN.)

 

4. READ the question AGAIN.  This time circle important information.  (#'s, action words like EACH)

 

5. Choose a strategy to organize your data:

 

      *T-Chart

 

      *Draw a picture

 

      *Draw a bar model

 

(The point of this step is to really VISUALIZE what the info in the problem means...  Do I have a total and I'm looking for a part?  Do I have the parts and I'm looking for the total?)

 

6. Correctly solve.

 

7.  Look back and make sure your answer MAKES SENSE and answers the question asked.

 

8.  Always, always, always check subtraction & division with the inverse operation.
Bar Modeling (this is a new strategy to me, too!  Some of the students really get it and love it.

 

 

 

 

If you're looking for a total = addition or multiplication

 

If the total is given and you are looking for a part of a total = subtraction or division

 

Addition and Subtraction = groups are NOT equal 

 

Multiplication and Division = groups are equal

 

Area of Rectangles:  Area = length X width (A=L x W)
Properties of Addition:
 Commutative property of addition:  order of addends does not change the sum (2+4=6  4+2=6)
 
Associative property of addition:  the grouping of the addends does not change the sum (2+4)+5 =11   or 2+(4+5)=11 {doesn't matter which you add first}
 
Identity property of addition: any number plus zero is that number  (7+0=7)
 
Inverse operation:  subtraction is the inverse (opposite) of addition                             (8+6=14  / 14-8=6)  {Fact Families}
 
 
 
Properties of Mulitplication:
 
Commutative Property of Multiplication:  4 x 6 = 6 x 4 (The order of the factors does not change the product)
 
Associative Property of Multiplication:  4 x (2 x 5) = (4 x 2) x 5 (Grouping of factors does not change the product.  Factors must be in the same order)
 
Distributive Property of Mulitiplication: 4(2 + 5) = (4 x 2) + (4 x 5)   
OR  4 x 7 = (4 x 3) + (4 x 4)
 
 

Finding the unknown:

Use the information given and the inverse operation or commutative property, then apply a multiplication or division strategy:  6 x n = 48  /  48 ÷ 6 = n (now this is just a division problem that the students have many strategies to solve)

n x 7 = 42  / 42 ÷ 7 = n

35 ÷ n = 7  /  35 ÷ 7 = n

 

Mutliplication vocabulary:  5X4=20

5 and 4 are factors

20 is the product

Multiplication strategies (strategies are ways to get the product for facts you don't know automatically)

Draw an array (rows X columns)

Draw equal groups  (5 circles with 4 stars in each 5X4=20)

Repeated addition (5+5+5+5=20)

Skip count (5, 10, 15, 20)

 

Division Vocabulary:  20 / 5 = 4

20 is the dividend (the total, the big number)

5 is the divisor (the number dividend is being divided by)

4 is the quotient (the answer)

Division Strategies:

Use related multiplication facts (fact family, number bond)

Equal groups (start with total and group by divisor)

Build an array

Repeated subtraction (start with total and subtract divisor over and over until you reach zero, how many times did you subtract?)

 

 

Fractions:

N = numerator {part}   D=denominator {whole} **remember denominator "down"

If N and D are the same = 1 whole {3/3 = 1}

If N is smaller than D, the fraction is < 1 {1/3 < 1}

If N is larger than D, the fractions is > 1 {3/2 > 1}

Any number over 1 = that whole number {4/1 = 4}

If N is 1/2 of D, the fraction is equivalent to 1/2 {3/6, 4/8, 5/10 = 1/2}

Ways to compare fractions:

Draw a fraction model, draw a number line, use the same D and same N rule.

RULES:

If the Denominators are the same, compare the Numerators.  The fraction with the larger Numerator is the larger fraction.

If the Numerators are the same, compare the Denominators.  The fraction with the SMALLER denominator is the larger fraction.