Young Sheldon - Season 4 Episode 18 : The Wild and Woolly World of Nonlinear Dynamics Full Episode Onlinebr br Let's visitbr Click Here ➭➭➭ br br br br br br br br br br br br br br br br br br Genre : Comedy, Familybr Network : NBCbr Cast: Mark-Paul Gosselaar (Zack Morris), Mario López (A.C. Slater), Dustin Diamond (Samuel "Screech" Powers), Tiffani Thiessen (Kelly Kapowski), Elizabeth Berkley (Jessie Spano), Lark Voorhies (Lisa Turtle), Dennis Haskins (Richard Belding)br br br br br br br br Storyline :br In an attempt to cheer Screech up enough to complete their science project, Zack pretends to know a girl who is interested in Screech, but things soon become complicated.