I've been using Chalk Dust materials the last three years for both Precalculus and Calculus. Last year, I received a perfect score on the SAT Subject Test for Mathematics Level 2, and I also scored quite well on the math sections of the SAT and ACT. Yesterday morning I took the AP Calculus AB exam, and I'm confident I'll receive college credit. I know your teaching played a large part in these successes, so I just wanted to drop you a note to thank you. I rate you among the very best teachers I've ever had. My younger sister, a junior, just finished Chalk Dust Precalculus, and my other sister has enjoyed enjoyed your sixth grade math this year. My mom recommends your materials to everyone. We all agree that you've been one of the single best parts of my high school career as well as my sister's. Again, thank you.