It puts boundaries on it. Learning shrinks to fit the testing process. In the British system, you might face tests only once a year. Meanwhile, you must constantly forge your own contexts to retain what you've learned. To what my students told me, I would add a fifth enemy of learning.
Kinetic energy is mass times half the velocity squared.
The Gulf Current flows here. . . . Science and math are no fun until you see into the abstractions that lie behind them. For America to find her way out of her educational hole, you and I will have to find the heart of math and science again. We teachers have to see the beauty in the intellectual processes behind math and science. Only then can we reach our students.