Why are my SAT scores so inconsistent?

<p>I did several practice tests from the college board book and i often got in the low 1800s to high 1800s. On the last practice test i took , which was a few days before the MAY SAT, i got an 1840. Cr: 600, Math :620, and Writing:620. BUT on the MAY SAT i got a 1690, CR:540, WR:540, Math: 610. Why is there such a gap in scores ?? Arent SAT practice tests supposed to highy correlate to the real SAT. Why is there such a strange case? I was nervous or distracted at all. I'm really confused and i seriously dont know what to do.</p>

<p>Luck. (filler)</p>