When test scores seem too good to believe

Greg Toppo:

Scott Mueller seemed to have an uncanny sense about what his students should study to prepare for upcoming state skills tests.
By 2010, the teacher had spent his 16-year career entirely at Charles Seipelt Elementary School. Like other Seipelt teachers, Mueller regularly wrote study guides for his classes ahead of state tests.
On test day last April, several fifth-graders immediately recognized some of the questions on their math tests. The questions were the same as those on the study guide Mueller had given out the day before. Some numbers on the actual tests were identical to those in the study guide and the questions were in the same order, the kids told other Seipelt teachers.