Plot

Slater is horrified when his girlfriend from Germany arrives at Bayside as a new student. Zack helps hide the relationship from Jessie, but it is only a matter of time before she finds out, and Slater must figure out where his heart lies.

For their science project, Screech and Kelly construct a machine which is supposed to reveal the compatibility between two people. It causes problems, however, when it seems to confirm Jessie's suspicion that Slater still has feelings for his old girlfriend, Jennifer, who has just moved to town. To add even more complication, Zack develops a crush on Jennifer, but she is still preoccupied with Slater.—Anonymous

A girlfriend from Slater's past transfers to Bayside, and Jessie gets upset. Screech's science experiment proves that old feelings die hard.