5 U2 SK Overview

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5
Unit 2:
Multi-Digit Whole Number & Decimal Fraction Operations
Focus Standards: 5.OA.1, 2; 5.NBT.1, 2, 5-7; 5.MD.1
MP: 2, 7, 8
Foundation Standards: 4.OA.1, 3-6
Description of Student Learning
In Unit 1, students explored the relationships of adjacent units on the place value chart to generalize whole number
algorithms to decimal fraction operations. In Unit 2, students apply the patterns of the base ten system to mental
strategies and the multiplication and division algorithms.
To link to prior learning and set the foundation for understanding the standard multiplication algorithm, students begin at
the concrete–pictorial level. They use number disks to model multi-digit multiplication of place value units, e.g., 42 × 10,
42 × 100, 42 × 1,000, leading to problems such as 42 × 30, 42 × 300 and 42 × 3,000 (5.NBT.1, 5.NBT.2). They then round
factors and discuss the reasonableness of their products. Students evaluate and write simple expressions to record their
calculations using the associative property and parentheses to record the relevant order of calculations (5.OA.1).
Place value understanding moves toward understanding the distributive property via area diagrams which are used to
generate and record the partial products (5.OA.1, 5.OA.2) of the standard algorithm (5.NBT.5). Students move from
whole numbers to multiplication with decimals, again using place value as a guide to reason and make estimations about
products (5.NBT.7). Students explore multiplication as a method for expressing equivalent measures. For example, they
multiply to convert between meters and centimeters or ounces and cups with measurements in both whole number and
decimal form (5.MD.1).
Students can use manipulatives (i.e.,
number disks) as an introduction to
division with multi-digit whole numbers
(5.NBT.6). 420 ÷ 60 is interpreted as 420
÷ 10 ÷ 6. Next, students round dividends
and two-digit divisors to nearby
multiples of 10 in order to estimate single-digit quotients (e.g., 431 ÷ 58 ≈ 420
÷ 60 = 7) and then multi-digit quotients. This work is done horizontally, outside the context of the written vertical
method. Students divide multi-digit dividends by two-digit divisors using the written vertical method. Students progress
to a new level of difficulty with a sequence beginning with divisors that are multiples of 10 to non-multiples of 10.
Students practice with single-digit quotients with and without remainders before progressing into two- and three-digit
quotients (5.NBT.6).
Students use their understanding to divide decimals by two-digit divisors with whole numbers (5.NBT.7). They apply the
work of the unit to solve multi-step word problems using multi-digit division with unknowns representing either the group
size or number of groups. There is an emphasis on checking the reasonableness of their answers draws on skills learned
throughout the unit, including refining their knowledge of place value, rounding, and estimation.
Curriculum, Instruction, & Assessment
Mathematics
June 2014
Vocabulary
decimal fraction
divisor, quotient, remainder
pattern
area model
multiplier
equation
estimate
renaming (to larger unit)
( ) parentheses
equivalence
exponent
rounding
digit
equivalent measures Multiple, product
unit form
Strategies, Tools, Models, Representation
 Area models (e.g., an array)
 Number bond
 Number disks
 Partial product (an algorithmic method that takes base ten decompositions of factors, makes products of all pairs, and
adds all products together)
 Partial quotient (an algorithmic method using successive approximation)
Assessment Support
Type
Mid-Unit Task
End-of-Unit Task
Format
Constructed response with
rubric UNIT PRE/POST
Standards Addressed
5.OA.1,2; 5.NBT.1,2,5,7; 5.MD.1
5.OA.1,2; 5.NBT.1,2,5,6,7; 5.MD.1
Further information can be found in the Unit of Study
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Common Assessments, Exit Tickets
Literature aligned to this unit
Vocabulary Cards
Writing Across the Curriculum –
CIA/Math click to link
 Go-to Websites
 Support for materials - including lessons!
Bridges Investigations ENY
Need assistance? Have questions?
Lesli Ficker (503) 399-2873
Susan Luna Title I (503) 399-2872
K-5 Mathematics, IS-CIA
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