Getting Davey Jones S3 E12

In the opening scene Marcia & her 2 friends are in Marsha's bedroom discussing who the are going to get to play at THEIR SENIOR Prom

That can't be right - they are not seniors

or am I missing something ?

and how did Ms Robbins (a teacher) Marsha Wallace, become a teacher vs being the sales lady selling Jan her black curly wig later in the show S2 E15 ?

They are ninth graders in a junior high that has grades 7-9. They are the senior class in that school. I grew up around the same time with a true junior high school (grades 7-9) and events for the ninth graders often had “senior” in the title (though we didn’t really call the ninth graders themselves “seniors”).

and how did Ms Robbins (a teacher) Marsha Wallace, become a teacher vs being the sales lady selling Jan her black curly wig later in the show S2 E15 ?

Actually it's possible. One day back in the 70's, my family and I walked into the local K-Mart. At the door was a security desk and working at that desk was one of my junior high school teachers. My mom explained that teachers didn't make that much and some would take part time jobs to make extra money.

How come no one in the Davy Jones Fan Club seemed to know that Mr. Jones was MARRIED at that time (and had two daughters)?

And why did they have to pick such a horrible song for him to sing?