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