Common Core Essential Elements Mathematics

Intersecting lines. 
Lines that cross. 
Inverse operations. 
Opposite/reverse operations (e.g., subtraction is the inverse operation of addition, which is why 4 + 5 = 9 and 9 
– 5 = 4; division is the inverse operation of multiplication, which is why 4 x 5 = 20 and 20 ÷ 5 = 4). 
Linear equation. 
An equation that is made up of two expressions set equal to each other (e.g., 
y
 = 2
x
 + 5) - A linear equation has 
only one or two variables and graph as a straight line.  See Hhttp://www.eduplace.com/math/mathsteps/7/d/index.html 
Line graph. 
A graphical representation using points connected by line segments to show how something changes over time.