Louis C. Leithold, a longtime high school mathematics instructor who influenced the way calculus is taught in schools across the country, died April 29 in Pacific Palisades, Calif. He was 80. Mr.

When Louis Leithold, an 80-year-old math instructor at Malibu High School, died of natural causes in April, just days before his class was to take the Advanced Placement calculus exam, his students ...

It was rare for Louis Leithold to miss a day at Malibu High School, where he taught Advanced Placement calculus for the past several years. He had been pounding theorems and proofs into the heads of ...

Louis Leithold, who died April 29, wrote a number of books on calculus and taught at the university level. But his real passion was teaching high school students, as he did late in his life at Malibu ...