(October 28, 1989) Rain Forest; Buoyancy; Pouring Catsup; "Lemons"; Cold Remedies (November 4, 1989) Caffeine; Butterfly Migration; Autumn Leaves; "Lemons"; Doppler Effect; Sloth (November 11, 1989) Surfing; Geothermal & Volcanoes; Luau; Sugar Processing; Hawaiian Language; Eel (November 18, 1989) Whale Watch; Sunspots; "Lemons"; Skunk (November 25, 1989) Milky Way; Epilepsy; "Lemons"; Inventors' Fair; Cuttlefish (December 2, 1989) DNA; Rube Goldberg Contest; Parrot Chat; Chewing Tin Foil; Seahorse (December 9, 1989) Marathons; Celestial Navigation; Cataracts Chat; "Lemons"; Echidna (December 16, 1989) Spinal Cord; Glue; "Lemons"; Dog Behavior (December 23, 1989) Cheese; Aging; Appendix Chat; Wolves (December 30, 1989) Supercomputer; Greenhouse Effect; House Creaking; Owl (January 6, 1990) Season 8 (1990–1991) Disney Cartoons; Skateboards; Smothers & Yo-Yos; "Lemons"; Turtles (October 13, 1990) Juggling; Greenwich; Echoes; Flies (October 20, 1990) Everglades; Tomorrow's World; Recycling Chat; Everglades Students (October 27, 1990) Demolition Derby; Stress; Topology Chat; Eagles (November 3, 1990) Kidney; Steve Allen & Music; "Lemons"; Swans (November 10, 1990) Blood; Physics Circus; Faxes; "Lemons"; Pronghorn (November 17, 1990) Helicopter; Isaac Newton; "Lemons"; Koala (November 24, 1990) Dyes; Billiards; Cheerios; "Lemons"; Cheetah (December 1, 1990) Desert Animals; Judo; Salt & Ice; Pigs (December 8, 1990) Hydro Power; Whitewater Rafting; Mold; "Lemons"; Weather Proverbs (December 15, 1990) Wildlife Census; Eggs; Inventors' Fair; Stone Crabs (December 22, 1990) Violins; Voyager; Rube Goldberg; "Lemons"; Kinkaju (December 29, 1990) Glaciers; Termites; "Lemons"; Alligators (January 5, 1991) Season 9 (1991–1992) Aerobic Exercise; Swimming & Weightlifting; Luge & Skating; Softball & Racewalking (October 12, 1991) Solar Cars; Steroids; The Amazing Kreskin; How A Foot Falls Asleep; Miniature Horses (October 19, 1991) Murder Mystery; Ted Nugent; Bats (October 26, 1991) Cancer Causes; Frisbees; Computer Virus (November 2, 1991) Sewers; Cancer Treatments; Dick Cavett; Porcupines (November 9, 1991) Mapping The Dig Site; Dating The Bones; Assembling A Dinosaur (November 16, 1991) Domed Stadium; Photosynthesis; Polarized Sunglasses; Amusement Park (November 23, 1991) Tears; Slinky Physics; Bar Codes; Aspirin; Camels (November 30, 1991) Soviet Space; Sky Blue; Inventors' Fair; Llamas (December 7, 1991) Acid Rain; High Jump; Potholes; Goats (December 14, 1991) Medical Quackery; Microwave Ovens; Dollar Changer; Golden Eagles (December 21, 1991) Telecommunications; Solar Eclipse; Blimp; Bear Cubs (December 28, 1991) Hip Replacement; Airbags; Paper Cuts; Potbelly Pigs (January 4, 1992) Season 10 (1992–1993) Television; Studio Tour; Post-Production; Satellites (October 10, 1992) Movie Stunts; Household Chemistry; Coffee & Cream; Musk Ox (October 17, 1992) Election Polls & Surveys; Electric Car; Ceramics; Cougars (October