Algebraic Expressions: Letters Meet Numbers

Grade 6 Mathematics Exploring Variables and Operations

What Do You Think?

If you have 3 apples and someone gives you some more apples, how would you write the total number of apples you have? What if you don't know exactly how many apples they gave you?

What is an Algebraic Expression?

A mathematical phrase that contains numbers, variables (letters), and operations Variables are letters that represent unknown numbers Examples: 3 + x, 2n, 5y - 4 No equal sign (that would make it an equation!)

Real Numbers vs. Variables

{"left":"Numbers we know: 5, 12, 100, 3.5\nOperations we know: +, -, ×, ÷","right":"Variables (letters): x, y, n, a, b\nCombined together: 5x, n + 7, 2y - 3"}

Expression Building Challenge

Work in pairs to create expressions for these situations: • The number of students in class plus 5 more • Twice your age • The cost of 3 pizzas if each costs $d • Your height minus 2 inches

Parts of an Expression

Terms: Parts separated by + or - signs Coefficients: Numbers multiplied by variables Variables: The letters (x, y, n) Constants: Numbers by themselves Example: 3x + 7 has two terms, 3 is a coefficient, x is a variable, 7 is a constant

Expression Evaluation Steps

Remember This!

Variables are like empty boxes waiting to be filled with numbers Expressions help us describe mathematical relationships Practice makes perfect - the more you work with expressions, the easier they become!