The finished documents are unchangeable because the mechanism that created them no longer exists. They soon take on the aura of holy writ, and are beyond criticism. This wouldn't matter much, except when they become the canon upon which national and state tests are based. The fourth problem with the standards, and perhaps the most basic of all, is their failure to acknowledge the sequential nature of scientific knowledge. For example, the principles of buoyancy can't be understood without prior understanding of density and balanced forces.
Density requires prior familiarity with mass, volume, and ratio.
Each of these concepts requires weeks of development. This is time well spent, because at each stage students are engaged in activities appropriate to their level of understanding. Buoyancy then is a capstone topic, drawing upon and interconnecting many previously explored ideas. I believe that standards should be derived from curricula, not the reverse. To allow for different curricula, the standards should specify a bare minimum of topics.