In seventh grade, students gain fluency in manipulating expressions and solving equations, including those with negative numbers and numbers expressed as fractions or decimals. Students compute with percentages and ratios and describe proportional relationships using numerical, graphical, algebraic and verbal representations. Students analyze and compare data from random samples and generalize to make inferences about populations. Students also work with probability, performing probability experiments and computing probabilities with probability models. Students compute areas, volumes and surface areas of regular and irregular shapes and solve problems involving angles, including drawing shapes to match given geometric conditions and classifying types of triangles.