# Expressions and Equations / What is an Equation?

Activity 4 of 18
In this lesson students investigate expressions and equations to develop what it means to have a solution to an equation.

## Planning and Resources

Objectives
Students should be able to distinguish between an expression and an equation.  They recognize that solutions to an equation are the replacement values for the variable that make the equation true.

Vocabulary
expression
equation
variable
solution

Standard:

## Lesson Snapshot

#### Understanding

As students begin their work with algebraic equations, they should learn to think and reason about the nature of the solutions: what values would make sense both numerically and in a given context; and how different equations representing the same situation can be related to each other.

### What to look for

Students should be able to note that a variable is typically represented by a letter and takes on multiple values as replacements. An expression is a mathematical phrase involving numbers, variables, mathematical operations, and mathematical symbols such as parentheses.

### Sample Assessment

If k can be replaced by any number, how many different solutions can the equation k+6=0 have?