Activities to help students develop three important elements of critical thinking in mathematics: recognizing patterns, using visual imagery, and logical reasoning. -- Pattern activities -- working as detectives to discern mystery numbers and numerical patterns -- Imagery activities -- using the imagination to explore symmetry, congruence, rotation, part-whole relations, similarity, mapping -- Logic problems -- finding winning strategies, applying deductive logic, solving number sentences, and classifying by attributes Blackline masters with answers keys.