Follow the Bouncing Bag
When Rudy and Penny go to Chslkzone in a park sidewalk, Rudy leaves his backpack under a bench. That backpack has the mini chalkboard with the portal to and from Chalkzone in it. But when Vinnie drives by and sees Rudy at the sidewalk, he wants to get his revenge and proof of Chalkzone. When he can't find out where Rudy went, he tries to pry open the backpack to figure out how to get into Chalkzone and find Rudy. When Rudy finds out what Vinnie is up to, he pulls the portal across Chalkzone and Vinnie chases the backpack with the portal in it across Plainsville.