Professor Television is a recurring Sesame Street segment, featuring Bill Irwin as the title character. The skits usually involved the professor demonstrating words, which always end in disaster.

Picture Theme / EKA Description
Open and Closed
Episode 3656
Professor Television tries to demonstrate open and closed, but his efforts backfire when the door does the opposite of what the sign says. So, he just puts up a sign saying "Nevermind".
Near and Far
Episode 3683
Professor Television tries to demonstrate near and far, with help from Maria's voice.
Episode 3713
Professor Television tries to demonstrate "Danger" by putting a "Danger" sign above a deep drop. The sign falls, however, so he gets a large flashing "Danger" sign, which traps him.
There are two variations of this skit, one featuring the announcer at the beginning and kid's voices saying "Danger", while another version has all dialouge muted.