Unless the class has been unusually sequestered they should have at least some significant prior knowledge of prices so if the entrance ticket is a dud, a whole rethinking must be undertaken. If the exit tickets indicate no lasting or firm understanding of cause & effect as it relates to prices then the teacher must reteach the lesson after making appropriate adjustments to content, form, and delivery. Should the T,P,S assessment yield wildly misinformed responses, teacher may choose to spend more class time examining prices of common items (look on Amazon) to spur discussion among class.