5-1    Models of Addition 

5-2    Zero and Opposites

5-3    Rules for Adding Positive and Negative Numbers

5-4    Combining Turns

5-5    Adding Positive and Negative Fractions

5-6    Adding Probabilities

5-7    The Commuatative and Associative Properties  

5-8    Solving ax + b = c

5-9    Polygons