Martin Lamb, John Malone, Daniel Boase-Jelinek, and Scott LewisIn a study of 744 Western Australian Year 8 and 9 students, three different types of misperception were identified when students performed linear transformations. To examine their particular perceptual problems, nine persistent misperceivers (those who misperceived in the same way on three tests) were given one-on-one remedial instruction. Case studies of two different types of persistent misperceiver are presented here, one involving angles, the other involving reflections, to demonstrate to maths teachers what may be happening in their classrooms unbeknown to them.