Grade 8 Big Ideas: Math Number represents, describes, and compares the quantities of ratios, rates, and percents. Computational fluency and flexibility extend to operations with fractions. Discrete linear relationships can be represented in many connected ways and used to identify and make generalizations. The relationship between surface area and volume of 3D objects can be used to describe, measure, and compare spatial relationships. Analyzing data by determining averages is one way to make sense of large data sets and enables us to compare and interpret.