The New Scooby and Scrappy-Doo Show Season 1 Episode 16
The kids go back to their high school for the Central High Carnival, and run into their old science teacher Mr.McDabble, who has created a ruby lazer that can cut through the hardest metal. But before too long, the ruby ends up missing, and the kids have to find out what happened.
Episode Title: Crazy Carnival Caper
Air Date: 1983-10-15