One season 18 episode, number unknown, introduced the character of Gina.

According to "Growing Up Gina", included in the December 17, 2010 issue of sesame family newsletter:

The script read that three students of Gordon’s science class were to accompany him up to the roof of 123 Sesame Street, and along with Big Bird, receive an inspiring lesson on the stars, galaxies, Big Dipper, Little Dipper and all the wonders of the world above us. Two students knew how to get to Sesame Street. One didn’t: Gina. That would be me. As Gordon and the gang sang songs and questioned the enormity of the sky, Gina desperately navigated her way through the neighborhood, while being barraged by honkers and attempting to get the green Muppet in the trash can to help her. I wish I could say it was my acting skills that made this particular segment so comically believable but it wasn’t.