In addition to the famous Scopes trial, there have been significant legal rulings that creationism is not science and cannot be taught as such. This is largely the result of the arbitrary definition that science must assume naturalism. Because of these rulings, the current approach is to teach people the truth of creation in whatever way possible (creation seminars, books, videos, the Internet, Christian home schooling) outside of formal secular science study.
It is unfortunate that there is a serious division in the creationist camp between those who believe the earth is young (about 10,000 years) and those who hold to the standard view of about 4.5 billion years. Just as diverse groups have come together to fight causes such as abortion, the fight against promotion of naturalistic evolution as science far outweighs the secondary issue of how long God took to create. Creationism can work with either a young or an old earth (without implying evolution), but evolution MUST have an old earth.
For those who WANT to teach science from a creationist perspective, there is a shortage of curriculum materials, and many times educators must settle for the textbook having the least emphasis on evolution.
A common statement made by evolutionists concerning creation science is "where is your science"? The reality is that creation research is hampered by a lack of funding for world-class facilities and support personnel. The ICR Graduate School is the leading creationist institution. The Creation Research Society also has a small laboratory.