Square One, for actual math information and skills that I can directly point to, and use even today (house numbers and sides of the street). This got me in trouble at school, as I'd learned all about things like negative numbers and decimals and fractions long before I was "supposed" to. I had teachers that generally knew what to do with me, but one just go so exasperated that she sent me to the office for "not doing what she asked" constantly on my math work. I still sing "less than zero" and had that in my head constantly watching the Olympic divers.
Mr. Wizard, for Cool Science Tricks and the reasons behind them (cutting a piece of paper so you can step through it, glue from flour, the reaction behind the essential baking soda & vinegar volcano, etc). It also taught me about the scientific method and how to go about figuring stuff out.
Animaniacs for general knowledge (e.g. the countries of the world song, what things are considered reference-able culture by my mom's generation, that WWII was really bad for a lot of people in various ways that are still felt today).
I know I watched Beakman's World and Bill Nye, but I don't remember learning overly much anything new from them, not that Mr. Wizard hadn't already touched on, anyway.
Cosmos for cool space stuff. Who has black hole facts in 1st grade? ME
Beyond 2000, a show on Discovery Channel about emerging technology. I can't say that it taught me anything specific, except how the tech industry worked in general and how most innovations will run into some snag when going from bespoke to mass production.