Question: Can the Investigations units be taught in a different order than suggested?
Answer: The first edition of Investigations was written as a “replacement unit” model where individual units within a grade were somewhat less dependent on previous units, and schools and districts often chose their own sequence, or decided to teach only 3 or 4 units the first year of implementation. That was the 1990s! The units in the 2nd and 3rd editions were written as a complete, coherent, full-year curriculum and are intended to be taught in order. Whether it’s because people remember the first edition, or have specific reasons or issues, we often get asked about changing the sequence of units.
In the 3rd edition, the curriculum units at each grade level are intentionally and carefully sequenced. We strongly recommend that the units be taught in the intended order. All of the units in the number and operations strands (whole and rational numbers) absolutely need to be taught in order because concepts and skills are introduced and developed, and then built upon over the course of the year. We purposefully spaced out the number and operations units across the year. Students need time to sit with the ideas and use them in other contexts, before moving on to new ideas. The non-number units that are in between these units often utilize and reinforce previously taught number concepts and skills, particularly in the work that is the main focus of that unit (e.g. geometry or data) as well as in the ongoing review and practice features (i.e. Classroom Routines/Ten-Minute Math Activities and Daily Practice pages). Changing the sequence of units means these features may focus on content that isn’t appropriate or timely.
We do recognize that, in some districts, decisions may need to be made about the order of units in a specific grade for various reasons, the most common being the timing of the state assessment, or beliefs or preferences about what content they think should come first. (See Why Start with Multiplication and Division?, a Grade 3 Q&A.) We advise schools/districts to complete an entire year of instruction using the intended sequence before making any decision(s) to change the order. Then, the decision should be made collectively, rather than by an individual teacher. Such decisions should only be made after careful scrutiny of what was learned from teaching the units in order, the specific math content of a unit, and its position in the grade level sequence. (Implementing Investigations at Grade X is a useful resource in providing information that traces the development of content ideas within and across grade levels, as well as information about how the math in the Classroom Routines/Ten Minutes Math Activities develops over time.)
Have you thought about changing the order of the units? Tried it? We’d be interested in hearing about your experiences.