From what I remember from the 70's/80's (and that's in the cobwebs of my mind) is:
big hair (have a big hair contest), platform shoes, polyester, the movie "Jaws", Farrah Fawcet, the Bee Gees, Studio 54, Delorean, and color, color, color!!
Get big rolls of translucent cellophame wrapping paper and string big sheets of it in geometric patterns.
Ya know those AOL CD's you get in the mail? I've been collecting them an they make good craft projects. Cut them up and paste them onto some poster board for a glittery effect to catch the light rays from the disco ball.
Has anyone had a disco dance at their elementary? If so, what did you do for decorations? We have a $150 budget. The DJ is providing a 'disco ball'. We need to decorate the gym and the cafeteria. Thanks!