Discrepant Event  
  Retrieved from- http://static.nsta.org/files/PB271Xweb.pdf  
  Discrepant-event science activities for use both in grades 5–12 classrooms and as models of inquiry-oriented science lessons for use in pre-service classes and in-service professional development settings.

Whether done as a hands-on activity or demonstration, the discrepant event’s surprising, often counterintuitive outcome creates cognitive disequilibrium that temporarily throws learners mentally off-balance. For example nearly everyone “knows” that a sharp needle will pop a balloon, but in Activity #20 learners observe a long, sharp needle skewer a balloon without bursting the balloon. The unexpected outcome of such a discrepant event generates a need-to-know that motivates learners to thoughtfully reconsider their prior conceptions.

Discrepant-event activities can be used anywhere in a unit. They are especially effective for diagnostic and formative assessment of learners’ evolving mix of science conceptions and misconceptions. Teaching science via multisensory experiences with live science phenomena also models the nature of science and contributes to memorable and transferable learning.

The activities were selected to meet the six criteria of being safe, simple, economical, enjoyable, effective, and relevant for both teachers and their students (see Appendix A for a discussion of the criteria).