Class clowns

You’ll feel smarter than a fifth-grader after sampling from nine straight hours of “Welcome Back, Kotter,” the 1970s sitcom that was determined to prove that you don’t have to study to be a standout student. The novelty of watching John Travolta in his formative years will wear off by the third episode; John Sebastian’s theme song, however, never gets old.

Noon Sat., Antenna TV

Tool time

The “This Old House — 40th Anniversary Special” looks back at how home renovation has changed over the years, and the role this iconic series played in that evolution. Original host Bob Vila straps on his tool belt one more time.

5 p.m. Sat., TPT, Ch. 2

Don’t go in the water

Star Ian Ziering and director Anthony C. Ferrante tip their toes back in the water with “Zombie Tidal Wave,” an all too obvious attempt to generate the buzz of their first collaboration, “Sharknado.” This adventure pales in comparison, in large part because Ziering’s co-stars don’t realize they’re supposed to deliver the cheesy lines with tongues firmly planted in their cheeks. By the fourth time a green-colored zombie bites into a skull, you’ll be praying for an offshore sighting of Tara Reid.

8 p.m. Sat., Syfy

Neal Justin