KEY CONCEPTS TO LEARN:

1. Number Lines & Measurement  
   • 1-D Distance = Positive difference between points x and y
     • d =|x – y|
   • Midpoint = Average of x and y, midpoint = (x+y)/2
   • Sum of the Parts = Whole
     • AB + BC = AC
   • Big secret to number line questions
     • most number line problems test 1 of 2 skills
       • ratios/proportions
         • e.g. AB:BC = 3:2 and AC = 50
       • add/subt fractions (common denominators)
         • e.g. A = 1 1/3, B = 2 5/8, length of AB = ?