I absolutely agree that the curriculum can, and should, be integrated. And professional development was integrated often and with good results when implemented.

My point was that conducting a combined math and science project where teachers have a choice in how they balance their engagement with professional development and pressure from high stakes state mandated assessment, resulted in mathematics as the topic of choice. This was in spite of initially offering more options in science.

Where we made our greatest strides in elementarry science was through tying it to new technologies.