Kirschner, Sweller, and Clark (2006) review of literature found that although constructivists often cite each other's work, empirical evidence is not often cited. Nonetheless the constructivist movement gained great momentum in the 1990s, because many educators began to write about this philosophy of learning.
Hmelo-Silver, Duncan, & Chinn cite several studies supporting the success of the constructivist problem-based and inquiry learning methods. For example, they describe a project called GenScope, an inquiry-based science software application. Students using the GenScope software showed significant gains over the control groups, with the largest gains shown in students from basic courses.
In contrast, Hmelo-Silver et al. also cite a large study by Geier on the effectiveness of inquiry-based science for middle school students, as demonstrated by their performance on high-stakes standardized tests. The improvement was 14% for the first cohort of students and 13% for the second cohort. This study also found that inquiry-based teaching methods greatly reduced the achievement gap for African-American students.
In a 2006 article, the Thomas B. Fordham Institute's president, Chester E. Finn Jr., was quoted as saying "But like so many things in education, it gets carried to excess... the approach is fine to some degree.". The organization ran a study in 2005 concluding that the emphasis states put on inquiry-based learning is too great.
Richard E. Mayer from the University of California, Santa Barbara, wrote in 2004 that there was sufficient research evidence to make any reasonable person skeptical about the benefits of discovery learning--practiced under the guise of cognitive constructivism or social constructivism--as a preferred instructional method. He reviewed research on discovery of problem-solving rules culminating in the 1960s, discovery of conservation strategies culminating in the 1970s, and discovery of LOGO programming strategies culminating in the 1980s. In each case, guided discovery was more effective than pure discovery in helping students learn and transfer.
It should be cautioned that inquiry-based learning takes a lot of planning before implementation. It is not something that can be put into place in the classroom quickly. Measurements must be put in place for how students knowledge and performance will be measured and how standards will be incorporated. The teacher's responsibility during inquiry exercises is to support and facilitate student learning (Bell et al., 769-770). A common mistake teachers make is lacking the vision to see where students' weaknesses lie. According to Bain, teachers cannot assume that students will hold the same assumptions and thinking processes as a professional within that discipline (p. 201).
While some see inquiry-based teaching as increasingly mainstream, it can be perceived as in conflict with standardized testing common in standards-based assessment systems which emphasise the measurement of student knowledge, and meeting of pre-defined criteria, for example the shift towards "fact" in changes to the National Assessment of Educational Progress as a result of the American No Child Left Behind program.