Writing expressions

Task goals

• Write an expression for a simple worded phrase involving one operation, e.g. "$n$ increased by $7$" or "$5$ times $k$".
• Write an expression for a phrase using reversed subtraction language, e.g. "$9$ less than $m$" versus "$m$ less than $9$".
• Distinguish an expression (no equals sign) from an equation (has an equals sign) and explain the difference.
• Write an expression for a two-step worded phrase, e.g. "double the sum of $x$ and $6$" or "triple $y$, then add $4$".
• Write an expression for a real-world context involving a fixed fee plus a variable rate, e.g. a booking fee plus a per-person charge.
• Write an expression for a standard geometric formula, such as the circumference or area of a circle, using a given variable for the radius.
• Verify a formed expression by substituting a given value for the variable and simplifying using GEMA.
• Evaluate whether a student's expression correctly represents a worded phrase or context, explain any error, and give the correct expression.