Signs of sums

The  exercise appears under the 7th grade (U.S.) Math Mission. This exercise explores the sign of the sum of integers.

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


 * 1) Determine the sign via number line: This problem provides a number line with two abstractly labeled points. The student is asked to determine the sign of the sum that results from adding the two points.Sos1.png
 * 2) Determine sign of sum: This problem presents a sum of two numbers. The student is asked to find the sign (positive, negative, or zero) of the sum.Sos2.png

Strategies
Knowledge of addition and subtraction on integers are encouraged to ensure success on this exercise.
 * 1) The sign can be positive, negative, or neutral (zero).
 * 2) When summing numbers, the larger magnitude dominates. So a larger negative number is negative and a larger positive number is positive.
 * 3) In the number line model move geometrically to improve efficiency.

Real-life Applications

 * 1) The ability to quickly determine if a value is positive or negative can be important in medical fields.
 * 2) The geometric interpretation of magnitude is important in physics and other sciences.