Investigations in Numbers, Data, and Space is a K–5 mathematics curriculum, developed at TERC in Cambridge, Massachusetts, United States. The curriculum is often referred to as Investigations or simply TERC. Patterned after the NCTM standards for mathematics, it is among the most widely used of the new reform mathematics curricula. As opposed to referring to textbooks and having teachers impose methods for solving arithmetic problems, the TERC program uses a constructivist approach that encourages students to develop their own understanding of mathematics. The curriculum underwent a major revision in 2005–2007.
Investigations was developed between 1990 to 1998. It was just one of a number of reform mathematics curricula initially funded by a National Science Foundation grant. The goals of the project raised opposition to the curriculum from critics (both parents and mathematics teachers) who objected to the emphasis on conceptual learning instead of instruction in more recognized specific methods for basic arithmetic.
The goal of the Investigations curriculum is to help all children understand the fundamental ideas of number and arithmetic, geometry, data, measurement and early algebra. Unlike traditional methods, the original edition did not provide student textbooks to describe standard methods or provide solved examples. Instead, students were guided to develop their own invented algorithms through working with concrete representations of number such as manipulatives and drawings as well as more traditional number sentences. Additional activities include journaling, cutting and pasting, interviewing (for data collection) and playing conceptual games.
Investigations released its second edition for 2006 that continues its focus on the core value of teaching for understanding. The revised version has further emphasis on basic skills and computation to complement the development of place value concepts and number sense. It is also easier for teachers to use since the format is more user friendly, though some districts have failed to carefully implement the second edition as well, and moved back to textbooks that teach traditional arithmetic methods.
A systematic review of research into Investigations was conducted by the U.S. Department of Education, Institute of Education Sciences and published as part of the What Works Clearinghouse in February 2013. This found "potentially positive effects" on mathematics achievement, supported by a "medium to large" evidence base.