The Saved By The Bell series first began as a pilot for NBC (National Broadcast Company), and the name of the show was Good Morning, Miss Bliss. The Good Morning, Miss Bliss pilot did air on NBC back in 1987 (it aired in The Facts of Life's timeslot). The pilot for Good Morning, Miss Bliss did not have any of the cast of Saved by the Bell (or even any of the later cast of Good Morning, Miss Bliss!). Instead, the pilot starred Hayley Mills, Brian Austin Green (of Beverly Hills, 90210 fame), and Jaleel White (of Family Matters fame)! In the pilot, "Miss" Bliss was actually a newlywed! Brian Austin Green did not play Zack Morris, or a "Zack Morris-like" character, he instead played a character who who super serious, and who always wore business suits to school. (similar to Michael J. Fox's character Alex P. Keaton on Family Ties).
Still, NBC passed on the project at that time), and The Disney Channel picked it up and filmed 13 episodes in 1988 for a winter 1988 and spring 1989 run on The Disney Channel.
Indeed, Good Morning, Miss Bliss was originally conceived as a vehicle for Hayley Mills, a popular actress who had done many previous movies for Disney. Mills played the character of a widowed junior high school teacher, Miss Carrie Bliss, and the show was mostly about her experiences as a teacher, as well as her hapless love life! The "Miss Bliss as a widow" storyline seems to be consistent with the pilot, and some believe that the Good Morning, Miss Bliss episodes with Zack and the other characters took place a year after the pilot episode. This was the first incarnation of "Saved by the Bell".
The setting for the show was John F. Kennedy Junior High School in Indianapolis, Indiana. For the remainder of Good Morning, Miss Bliss's run, Zack Morris (Mark-Paul Gosselaar), Samuel "Screech" Powers (Dustin Diamond), Lisa Turtle (Lark Voorhies) and Principal Richard Belding (Dennis Haskins) were the other main characters in the show. However, there were joined in the show by Nikki Coleman (Heather Hopper), Mikey Gonzalez (Max Battimo), and Milo Williams (T.K. Carter), who were never in later seasons of the Saved by the Bell show. Also, the focus of Good Morning, Miss Bliss was Miss Bliss first, and basically Zack Morris second. The show was produced by Peter Engel, and William F. Phillips was the Executive in Charge of Production. After the move to NBC, some of the Good Morning, Miss Bliss episodes were rerun on NBC in the summer after the Grade 9 season along with an introduction by Zack explaining that this was what happened to him "in junior high". In any case, it is the absence of Kelly Kapowski, Jessica Spano, and A.C. Slater, and the setting of the school in Indianapolis that account for the most glaring continuity lapse of the Saved by the Bell series.
There were 13 episodes made of Good Morning, Miss Bliss, but Disney decided not to continue with the project. So it appears Producer Peter Engel, William F. Phillips, et al. took the show back to NBC which then decided to pick up the project again, as its first live action show for NBC's Saturday morning line up. Major changes were made for the show's second incarnation. First the name of the show was changed to Saved by the Bell. The setting was changed from John F. Kennedy Junior High School in Indianapolis, Indiana to Bayside High School in Pacific Palisades, California, which is southwest of Los Angeles and Santa Monica. The characters of Zack Morris, Screech Powers, Lisa Turtle and Principal Richard Belding were kept for the show, and three new main characters were added: Kelly Kapowski (Tiffani-Amber Thiessen), Jessie Spano (Elizabeth Berkley) and new transfer student, A.C. Slater (Mario Lopez). The other characters, including Miss Bliss, were dropped. And, of course, the focus of the show changed to Zack Morris, and to a lesser extent his friend Screech. Some of the original production crew of Good Morning, Miss Bliss did not stay on for Saved By The Bell, though some other members of the crew continued on with the show as Saved By The Bell.
But this introduces the first continuity questions. How is it that three students and a principal can move 2000 miles between junior high and high school and still stay together in the same school? Why does Zack tell Slater in the first episode of Grade 9 that he's been after Kelly for the previous "2 years and 6 boyfriends" when no mention is made of her in Good Morning, Miss Bliss? Why is no mention made of Zack's good friends Nikki and Mikey from Good Morning, Miss Bliss in the Saved By The Bell series; and why is no mention made of Zack's friend since the first grade, Jessie, in Good Morning, Miss Bliss? Why is Zack's father's name Peter Morris in Good Morning, Miss Bliss, and Dereck Morris in Saved By The Bell (and why do different actors play Peter and Dereck)? Why is it said in Good Morning, Miss Bliss that Zack's father and mother are divorced when they clearly are not divorced in Saved By The Bell? Why is mention made of Screech having a brother in Good Morning, Miss Bliss, when it is clearly stated that he is an only child in Saved By The Bell? What is the explanation? The only explanation for this is that there is no good explanation (unless you want to count alternate realities). Saved by the Bell is a farce by nature, and its characters and gags were the main focus of the show. Unfortunately that means that the plot and the show's continuity must (and did) take a back seat to character development and to the comedy in the series, especially in its change from Good Morning, Miss Bliss on Disney, to Saved by the Bell on NBC.
The show moved to NBC in 1989, soon to become the network's first live-action hit since Land of the Lost in 1977. Playing with the big boys now, the show got rid of its title character as well as its title. Now known as Saved by the Bell, the new show featured Zack, the "preppie" stud, Screech, the nerd, and Lisa, the aspiring dress designer, as well as their new friends Slater, the handsome jock, Kelly, the boys object of desire, and Jessie, the intelligent girl (who was just as pretty and well-dressed as the other two girls, but no one seemed to notice).