How do you know that kit-based science instruction is better than traditional science instruction?

A great deal of research has come out in the past 5 years that supports higher student scores on standardized tests in science for kids who are engaged in this kind of science. In addition, scores for student go up dramatically in reading, writing and math when science is taught this way in an integrated fashion. See Mike Klentchy's report on his results in El Centro, CA as well as the data from Pittsburg's ASSET Program.