Class-testing version organized around a series of 24 scientific concepts (or great ideas). It begins with the idea that the universe can be studied by observation and experiment. Encompasses physics, chemistry, astronomy, biology and earth sciences, focusing on general principles and their application to authentic situations rather than esoteric detail. Integrates the sciences rather than treating them separately. Offers students the ability to place major public issues such as the environment, energy and medical advances in a scientific context.