Grade 4-B contents & samples - Math Mammoth

Chapter 8: Decimals
Introduction
In fourth grade, we study decimal numbers with one or two decimal digits, and add and subtract them. It
is important that the student grasps these simple topics well, because we are laying a groundwork towards
fifth and sixth grade, where decimal operations and using decimals take a “center stage.”
For now, the focus is first of all, understanding the fact that decimals are simply fractions with a
denominator 10 or 100. Then with that in mind (decimals are fractions), we study comparing, adding, and
subtracting them.
Notice:
In the addition problem 0.5 + 0.9, we get 14 tenths, which is 1.4. A common student misconception
is to add 0.5 + 0.9 = 0.14.
In a problem such as 0.5 + 0.11, a common student misconception is to get 0.16. Such students are
thinking of the decimal parts as if they were “whole numbers.” To solve 0.5 + 0.11 correctly,
students can rewrite 0.5 as 0.50, and then the problem becomes 0.50 + 0.11 = 0.61.
In the lesson Using Decimal Numbers, students use decimals with some metric measuring units, including
converting between units. This topic will also be studied further in 5th grade.
The Lessons in Chapter 8
page span
Decimal Numbers—Tenths.................................................... 172 2 pages
Adding and Subtracting with Tenths ..................................... 174 2 pages
Two Decimal Digits—Hundredths ........................................ 176 4 pages
Adding and Subtracting Hundredths ...................................... 180 4 pages
Adding and Subtracting Decimals in Columns .................... 184 3 pages
Using Decimals with Measuring Units ................................ 187 2 pages
Mixed Review ...................................................................... 189 2 pages
Review .................................................................................. 191 2 pages
Sample worksheet from
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