By Thursday the Grease rehearsals had fallen into a routine, with the cast and ensemble players acclimating themselves to the songs they must sing, as well as co-director Pierrette Jensen's living room.

How relaxed? So relaxed director Staci Johnson's toddler felt sufficiently comfortable to drop her diapers in front of the whole crowd to the non-plussed amusement of one and all. Now that's stage presence.

After recapitulating the songs learned the day before, Johnson took them into new territory playing "Rock 'n' roll Will Never Die" -- a song which was in the movie but not the musical. Johnson has added to The Acting Company production to walk the audience back in from the intermission and settle them down.

She also got them all into "Summer Nights" a group counterpoint piece between Danny and the Burger Boys and Sandy and the Pink Ladies;; with the ensemble singers contributing "oo-oo-oos" and "uh-huhs, uh-huhs" for background and bass line.

When they got to "You're the One I Want" Colleen Sullivan (Sandy) rose to her feet to sing her solo with backup song singers. This number brings up the issue of just which graduating class of Rydell High are we really talking about here?

Many believe it to be the Class of '55. The doo-wop sound of many of the songs support that. But certain factual anachronisms in the script and songs would rule 1955 out.

For one thing, one of the Burger Boys talks about an Impala, a Chevrolet model which didn't come out until 1958. Until then, the top of the line Chevy sedan was the Bel Air, the '57 model of which has for many come to represent the vehicular apotheosis of the hard core rock 'n' roll age.

Moreover, certain songs in "Grease! are clearly derived from songs, styles and sounds that didn't come along until the 60s. "Greased Lightning" is a clearly a paean to the Beach Boys-Jan & Deansurfer sound. Think "Little Deuce Coupe," "'Til Daddy Takes Her T-Bird Away."

"You are the one I want" sounds and moves very much like a 60s song to which go-go girls in high-top white plastic boots would have exuberantly done "The Swim," one of those manufactured -- albeit popular -- dance crazes that followed "The Twist."

The Grease book, music and lyrics, were written by Jim Jacobs and Warren Casey. Barry Gibbs, of the BeeGees, apparently added a title tune to the movie production. Several the 20 songs that have been associated with various productions of Grease were the work of other rock 'n' roll artists and writers.

The songs we most associate with rock 'n' roll are the ones we heard in high school.

Casey "was born in Yonkers, NY, and was an art major at Syracuse Univ. After teaching in upstate NY, he moved to Chicago in 1962, where he held a variety of jobs but soon gravitated towards acting and writing songs. He acted with the Chicago Stage Guild, the Old Town Players and the Kingston Mines. The Kingston Mines, the first company to suspect anyone might listen to his songs without a can of beer in his hand, staged the original production of Grease. With Jim Jacobs, he wrote Island of the Lost Coeds, a musical satire of the B-movies of the 1950s. He died in 1988," according to an Internet biography.

While this piece -- the only one I could find, none came up for Jacobs -- doesn't give Casey's high school graduation year, but the fact that he'd already been teaching and was moving to Chicago in 1962 suggests he probably graduated high school '58, or '59.

The early 60s sounds were probably the product of when Jacobs and Casey were actually writing the play.

So based on all those inferences and circumstantial allusions, I'm going to place the play's Rydell High time frame from the fall of 1957 when all the kids go back to school and graduation day June, 1958.

Because Casey grew up in New York, I'm going with an East Coast venue for Rydell High, despite the California Locale the movie gave it. Besides, California never had the same kind of hotrod "Greasers" the play focuses on. Not like Jersey and Brooklyn, anyway.

Furthermore, I'm assuming Rydell High is named after Bobbie Rydell, a classic rocker from one of the mid-Atlantic states, I believe.

All this is arbitrary, I know, but, hey, it works.

[Editor's note: see this for a list of all the songs that have been connected with stage and screen productions of Grease.]