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Positive and Negative Integers - Download as DOC

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					Lecture 10 -

                                              Key ideas

Positive and Negative Integers
       Using thermometer to show movement
       Starting/finishing position
Deficit model
   Presents problems as it means absence as in $
Vector model
   Is best as using movement is better for students understanding

Subtracting a negative
   Use idea of difference (equal additions)
Multiplying a negative by a positive
   Reverse so it will make sense
Multiplying a negative by a negative
   Use the distributive law
   5  (3  3)  0  5  3  5  3  0  15  15  0

Powers
  23  2  2  2  8      yes
                                       1           1                              1
 2 3  2  2  2  8      no         or        2 3  2 3  2 01  8      1
                                       23          8                              8
   1            1

24  12
   2
              24 2  24



                                       Discussion Questions
What is the generalisation
 499  500  500  499
and  500  499  500  499 but with a negative sign on it.

Why does this not make sense  3  5  15
Three negative people had $5 each …..

 5  3  5  3  0  15  15  0

Why Vector method using number line
   1      1     1 1
                 
24  24  24
   2      2     2 2
                       241
  1

17  3 17  3 17  3 17  17 1  17
  3
                                      Ideas to try

Use:
       Thermometers
       Number lines of various sorts (beaded etc.)

Bring in concept of equal addition

Use times as ‘lots of’ for groups of negative numbers

Concept of free choice /look again/ choose wisely


                                         Links
                 AC – EA                                EA – AA




                 AA – AM                                AM - AP

Teaching Addition and Subtraction
Book 5
Dollars and Bills (50)
Hills and Dales (50)
Teaching Algebraic Thinking and
Number Sense Book 8
6 minus 8 does work (31)
Figure It Out
N3 Walking the Plank (23)
       The Volcanoes Erupt (20)
       Chilly Heights (22)
N7/8 It’s a Try (8)
       Lifting Weights (9)
       Integer Zap (10)
       Shifty Subtraction (15)
       Judo Competition (14)

Nelson Maths Connecting Number
facts to Applications
Book 3 page 121 lesson 9-11
Book 4 page 156 lessonj 8


Powers Theta textbook page 13 and
page 68

				
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