[Note: This class did not do Unit M so this is their very first experience of model building.] During the class discussion of initial models Group 3 presents their initial model for static electricity. This model represents uncharged objects as containing no charged entities at all. The instructor prompts the class to discuss the model and the group proposes friction and heating as a reason why rubbing causes objects to become charged.
Group 5 works though STEPS 1-3 of Exploration #1. They hypothesize that the tinsel on the electroscope becomes positively charged and make appropriate predictions for the results of the experiments they see in STEP 3.
Group 5 show their model for what happens when acrylic and Styrofoam are rubbed together and express some confusion as to how uncharged objects should be represented. From Group 3's response it seems they are interpreting the charged entities in models as being more macroscopic in nature; this could lead to locally charged areas even on uncharged objects.