In this lesson, students solve problems about percent error, a way to describe error as a percentage of the actual amount. They interpret situations and identify which value is the correct amount that the error should be compared to. They make sense of problems as they solve for the erroneous value, the correct value, or the percentage (MP1). They also consider error tolerance expressed as a maximum acceptable percent error to determine values that fall within or outside of the range. As students relate situations involving percent error to previous work they have done with percent increase or decrease, they are making use of structure (MP7).