A variable represents an unknown or changing quantity and can be used in expressions, equations, and pattern rules to describe relationships among quantities. Learners interpret symbols as numbers rather than labels, translate verbal situations or tables into equations such as , and evaluate an expression when a value is given; formal manipulation of multiple variables, generalized functions, and abstract algebraic systems is beyond this level.
A variable is a letter or symbol that stands for an unknown number. We can use it in an equation to describe a situation.
Example:
Sam has some stickers. He gets 7 more stickers and now has 19 stickers. How many stickers did Sam have at first?
Find the unknown quantity.
The number of stickers Sam had at first is unknown.
Choose a variable.
Let represent the number of stickers Sam had at first.
Write an equation.
Sam’s starting stickers plus 7 equals 19:
Find the value of the variable.
Ask, “What number plus 7 equals 19?” Since , .
Check the answer.
Sam had 12 stickers and got 7 more:
So, Sam had 12 stickers at first.
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