 In 1986 he helped found the Calculus Consortium , which has published a successful and influential series of " calculus reform " textbooks for college and high school , on precalculus , calculus , and other areas . His " credo for this program as for all of his teaching was that the ideas should be based in equal parts of geometry for visualization of the concepts , computation for grounding in the real world , and algebraic manipulation for power . " However , the program faced heavy criticism from the mathematics community for its omission of topics such as the mean value theorem , and for its perceived lack of mathematical rigor . 
