Complex sentence: The National Center for Science Education (NCSE) is a nonprofit organization affiliated with the American Association for the Advancement of Science that defends the teaching of evolutionary biology and opposes the teaching of religious views in science classes in America's public schools.
Split into simpler sentences: The National Center for Science Education (NCSE) is a non-profit organization affiliated with the American Association for the Advancement of Science. It defends the teaching of evolutionary biology and opposes the teaching of religious views in science classes in America's public schools.