Writing Expressions with Variables
Grade 6 Mathematics Using Letters to Represent Numbers
What Are Variables?
Letters that stand for unknown numbers Can be any letter: x, y, z, a, b, n Help us write mathematical expressions Make math problems easier to solve
Variable Hunt
Find the variables in these expressions: 5 + x y - 3 2 × n a ÷ 4
Writing Expressions from Words
'Add 7 to a number' becomes n + 7 'Subtract 4 from x' becomes x - 4 'Multiply y by 6' becomes 6 × y or 6y 'Divide a number by 3' becomes n ÷ 3
Key Words to Mathematical Operations
{"left":"Add: plus, sum, total, more than, increased by\nSubtract: minus, difference, less than, decreased by","right":"Multiply: times, product, of, doubled, tripled\nDivide: quotient, split, shared equally, per"}
Practice Time!
How would you write: '5 more than a number' Think about it... What operation? What variable?
Expression Builder Challenge
Work with a partner to write expressions for: A number decreased by 8 Three times a number A number divided by 5 10 more than twice a number
Today We Learned
Variables are letters that represent unknown numbers We can translate word phrases into expressions Key words help us identify operations Practice makes perfect!