Idea 10of 23Builds onPut a number in for the letter
Expression or equation?
What makes an equation different from an expression?
Today you'll discover
- what the equals sign adds
- why an equation can be true or not
- how to spot each kind
Think first3n + 2 on its own
Which one is an equation?
Decide first, then press Next. Look for the equals sign.
Three bags marked n and 2 loose squares, with the expression 3n + 2 under them labelled expression: one value. Then the equation 3n + 2 = 17 under it, labelled equation: two sides equal. With 5 in each bag, 3 × 5 + 2 = 15 + 2 = 17: true. The last step shows four boxes of n and 1 loose bead.
See the whole ideathe big idea and the key word, in one place
The big idea
An expression is one value; an equation says two values are equal.
Compare themExpression: 3n + 2, a value. Equation: 3n + 2 = 17, a sentence that is true or not true.
Easy to get wrongAn equation can be written either way round: 17 = 3n + 2 says the same thing.
Key word
- equation
- two sides joined by =, saying they have the same value
Ready to use it?
- Sort expressions from equations.