Three line graphs. All have an x axis labeled ‘percentage of students proficient’ where the numbers range from twenty five to one hundred in intervals of twenty five. All have a y axis labeled ‘school year ending’ and have numbers ranging from two to fourteen in intervals of two. The first graph , titled ‘Variation one: equal annual increases has a line running from the lower left corner straight to the upper right corner. The second graph, titled ‘Variation two: three-year increases’ has a line that progresses from the lower left corner to the upper right corner in a staircase fashion where each horizontal line spans an increment of three. The third graph, titled ‘Variation three: combination’ has a line that runs between twenty five and fifty on the y axis in a staircase fashion and then goes straight to the upper right corner from fifty to one hundred.