Here are links to the most recent student e-textbooks -
Transitions: E-Textbook Link
Algebra 1: E-Textbook Link
Geometry : E-textbook Link
Advanced Algebra: E-Textbook Link
Functions, Statistics, and Trigonometry (FST): E-Textbook Link
Pre-Calculus and Discrete Mathematics: E-Textbook LinkUCSMP is the University of Chicago School Mathematics Project