Integer addition and subtraction: equations and number lines

The  exercise appears under the 7th grade (U.S.) Math Mission. This exercise uses a geometric model, the number line, to understand addition and subtraction of integers.

Types of Problems
There are two types of problems in this exercise:


 * 1) Write an equation for the diagram: This problem has a number line with some integers being represented and operated upon. The student is expected to find the result of the expression and write an equation to represent it.Iaaseanl1.png
 * 2) Write in the missing values: This problem has a number line with some integers represented and an operation on them. The student is asked to fill in the blanks with correct values to represent the result.Iaaseanl2.png

Strategies
Knowledge and familiarity with the number line model of addition and subtraction are encouraged to ensure success on this exercise.
 * 1) On the number line, movement forward or up is positive, and left or down is negative.
 * 2) Movement on the number line can be though of moving or stepping forward or backwards.
 * 3) Any equation should work on the first problem type so be creative!

Real-life Applications

 * 1) Familiarity with operations on integers will lead into comfort with other more advanced numbers, such as radicals, fractions and even imaginary numbers.