So the theory of evolution is taught in public schools as fact (one scientist even objected to stickers on his textbook stating that evolution was a theory) but the hypothesis of ID cannot even be mentioned.
Did any schools refernece the concept of Gia in the 1990s? Even in a non-serious manner as Earth Day approached?
The theory of evolution is taught as a theory. That's why its called a theory. But it is a well-supported theory, having been tested and strengthened by 150 years of research. Look at the whole field of genetics and DNA. If the evidence from DNA said Darwin's theory was wrong it would have been dropped like a hot potato, but instead it just supported the theory. When a scientific theory is this well-supported, Las Vegas wouldn't give you very good odds on overturning it (in other words, badmouth evolution all you want, but don't bet the rent money on its early demise).
The fact that change through time occurs is a fact. The explanation for that fact is the theory of evolution.
ID is based on religious belief and so has no place in science classes.
"Did any schools refernece the concept of Gia in the 1990s? Even in a non-serious manner as Earth Day approached?"
No. That's mythology, not science.