# ALEX Classroom Resource

## Grade 5 Mathematics Module 1, Topic D: Adding and Subtracting Decimals

Classroom Resource Information

Title:

URL:

Content Source:

EngageNY
Type: Lesson/Unit Plan

Overview:

In Module 1, Topics D through F mark a shift from the opening topics of Module 1. From this point to the conclusion of the module, students begin to use base ten understanding of adjacent units and whole-number algorithms to reason about and perform decimal fraction operationsaddition and subtraction in Topic D, multiplication in Topic E, and division in Topic F (5.NBT.7).

In Topic D, unit form provides the connection that allows students to use what they know about general methods for addition and subtraction with whole numbers to reason about decimal addition and subtraction (e.g., 7 tens + 8 tens = 15 tens = 150 is analogous to 7 tenths + 8 tenths = 15 tenths = 1.5). Place value charts and disks (both concrete and pictorial representations) and the relationship between addition and subtraction are used to provide a bridge for relating such understandings to a written method. Real-world contexts provide opportunities for students to apply their knowledge of decimal addition and subtraction as well in Topic D.

Content Standard(s):
Tags: add, baseten, compare, decimals, digits, divide, expanded form, hundredths, multiply, pattern, place value, subtract, thousandths, unit form