The document is a letter from a math teacher recommending that students take Calculus Research Lab (CRL) along with AP Calculus. CRL is a half-year honors course that uses computer algebra systems like SAGE, OCTAVE and R to solve calculus problems graphically, numerically and analytically. Topics covered in CRL include Python, functions, limits, derivatives, integrals, sequences, series, differential equations, vectors, and plots. The teacher believes CRL will deepen students' understanding of calculus and better prepare them for the AP exam. Students are asked to fill out a form indicating their interest in taking CRL next year.