Forming measurement expressions

Task goals

• Choose the appropriate measurement rule (perimeter, area, volume, or a unit conversion) before forming an expression for it.
• Form and simplify a perimeter expression from variable side lengths, using brackets to group related lengths before simplifying.
• Form an area or volume expression from variable dimensions, keeping units consistent throughout.
• Form an expression involving a fraction or an irrational constant such as $\pi$, e.g. the area of a semicircle of radius $r$.
• Form an expression for a real measurement context such as distance, capacity, mass, time, or a unit conversion.
• Distinguish a measurement expression from a formula or an equation, and explain the difference.