Lesson 4: What happens in the worms' cells during regeneration?

In this lesson, students learn about regeneration at the cellular level by studying cell division, a necessary component of regeneration, using their recently cut planarians as a model. At this point in the unit, the students have observed the planarians at the behavioral level and have started to investigate regeneration, one of the observed behaviors, at the phenomenological level. In this lesson, students develop models of cell division in order to explain how regeneration occurs in planarians. After developing initial models, students revise their models based on a list of criteria. The lesson includes two different lists, one that is appropriate for introductory biology and one that is appropriate for an advanced biology class. The lesson culminates with students documenting and explaining their models with another group to identify key characteristics in each model.