The Interactive Mathematics Program (IMP) is a four-year, problem-based mathematics curriculum for high schools. It was one of several curricula funded by the National Science Foundation and designed around the 1989 National Council of Teachers of Mathematics (NCTM) standards. The IMP books were authored by Dan Fendel and Diane Resek, professors of mathematics at San Francisco State University, and by Lynne Alper and Sherry Fraser. IMP was published by Key Curriculum Press in 1997  and sold in 2012 to It's About Time.
Designed in response to national reports pointing to the need for a major overhaul in mathematics education, the IMP curriculum is markedly different in structure, content, and pedagogy from courses more typically found in the high school sequence.
Nearly every one of these distinctive characteristics has generated controversy and placed the IMP curriculum right in the middle of the “math wars,” the conflict between those that favor more traditional curricula in mathematics education and the supporters of the reform curricula that were largely an outgrowth of the 1989 NCTM standards.
IMP is among the reform curricula that have been heavily criticized by organizations such as Mathematically Correct. That organization's Internet site begins with a statement that “advocates of the new, fuzzy math” (focus) “on things like calculators, blocks, guesswork, and group activities and they shun things like algorithms and repeated practice. The new programs are shy on fundamentals and they also lack the mathematical depth and rigor that promotes greater achievement.” Former NCTM president Frank Allen states, “Trying to organize school mathematics around problem solving instead of using its own internal structure for that purpose … (is destroying) essential connections….”
Criticism often includes anecdotal evidence including stories of school districts that have decided to discontinue or supplement use of the IMP curriculum and of students who did not feel they had been prepared adequately for college. "Regular math is much better, it makes much more sense," says Aimee Lynn Stearns, a student at Taos High School in Taos, New Mexico.
On the other hand, some IMP students describe the program in positive terms. "It's fun, but it makes you really think," according to Ziouck Gonzalez, a student at Wells High School in Chicago, Illinois. Looking beyond student response, IMP was one of five mathematics education programs designated "exemplary" by the US Education Department in 1999, for "outstanding quality and demonstrated effectiveness." It's About Time, the publisher of IMP, points out “the IMP first edition was published after more than 10 years of research, pilot testing, evaluating, field testing, revising, and detailed reviewing.”
Supporters point to statistical studies that compare the performance of students enrolled in IMP courses with their peers enrolled in traditional high school mathematics courses. Merlino and Wolff, two such researchers, report that in their several studies IMP students consistently outperformed traditionally taught students on both the math and verbal sections of the PSAT, as well as on the SAT-9. Kramer reported that grade 12 IMP students in his study performed better on all areas of mathematics tested by the NAEP test, and Webb and Dowling reported IMP students performed significantly better on statistics questions from the Second International Mathematics Study, on mathematical reasoning and problem solving tasks designed by the State of Wisconsin, and on a quantitative reasoning test developed by a university to administer to entering students. Taos High School began using the Interactive Math Program (IMP) in the 2006-07 school year. After three years of IMP classes, the initial cohort of 134 Taos High School juniors took the state mandated 11th grade Standards Based Assessment (SBA) in April, 2009. The SBA places students in one of four groups: Beginning Steps, Nearing Proficiency, Proficient and Advanced. The test results were compared with the SBA test scores of the previous two cohorts of juniors who had taken the SBA test after three years of traditional math instruction. The state test placed 53% of the 2009 IMP cohort in the proficient or advanced categories while the 2008 traditional math cohort’s proficiency rating was 43% and the 2007 cohort’s was 38%; roughly a combined 12% less than the IMP students (p < 0.025). The performance of the 2009 juniors was also analyzed over time. In 2006, the 2009 juniors were in 8th grade and 40% tested proficient or above in the 8th grade SBA. After three years of IMP, the percentage of these same students who now tested proficient or better had risen to 52% (p < .05). Students from the IMP cohort subsequently attended colleges and universities such as Stanford, Harvard, Carnegie Mellon, University of New Mexico and New Mexico State, among many others.
The other four NSF funded high school curricula projects: