Unit Summary
In this unit, 4th grade students explore the concept of multi-digit division and its applications, such as interpreting a remainder in division word problems and using division to determine the $$n^{\mathrm{th}}$$ term in a repeating shape pattern.
Students developed a foundational understanding of division in 3rd grade, when they came to understand division in relation to equal groups, arrays, and area. They developed a variety of strategies to build towards fluency with division within 100, and they applied that knowledge to the context of one- and two-step problems using the four operations. Students also came to understand the distributive property, which underpins the standard algorithm for division.
Just as at the beginning of the previous unit when students expanded their understanding of multiplication beyond 3rd grade understanding to include multiplicative comparison word problems, this unit starts off with introducing students to division problems with remainders, including interpreting them based on the context of the situation (4.OA.3). Next, students focus on extending their procedural skill with division to include up to four-digit dividends with one-digit divisors (4.NBT.6), representing these cases with base ten blocks, the area model, partial quotients, and finally the standard algorithm, making connections between all representations as they go. The use of the area model serves to help students conceptually understand division, and as a connection to their work with area and perimeter (4.MD.3), a supporting cluster standard. Lastly, armed with a deep understanding of all four operations spanned over the last three units, students solve multi-step problems involving addition, subtraction, multiplication, and division, including their new problem situations such as multiplicative comparison and interpreting remainders (4.OA.3). They also explore number and shape patterns, using the four operations to draw conclusions about them (4.OA.5).
Throughout the unit, students are engaging with the mathematical practices in various ways. For example, students are seeing and making use of structure (MP.7) as they “decompos[e] the dividend into like base-ten units and find the quotient unit by unit” (NBT Progressions, p. 16). Further, "by reasoning repeatedly (MP.8) about the connection between math drawings and written numerical work, students can come to see multiplication and division algorithms as abbreviations or summaries of their reasoning about quantities” (NBT Progression, p. 14). Lastly, as students solve multi-step word problems involving addition, subtraction, and multiplication, they are modeling with mathematics (MP.4).
After this unit, students will extend their conceptual understanding of multi-digit division to computations with two-digit divisors in 5th Grade Math (5.NBT.6) and to fluency with the division algorithm in 6th Grade Math (6.NS.2). Every subsequent grade level depends on the understanding of multi-digit division and its algorithms, making this unit an important one for students in 4th grade.
Pacing: 19 instructional days (16 lessons, 2 flex days, 1 assessment day)