Page 117 - Basic College Mathematics with Early Integers

94 C HAPTE R 1 I THE WHOLE NUMBERS

Chapter 1 Group Activity

Modeling Subtraction of Whole Numbers • Make as many pairs that include one object of each
type as possible.
A mathematical concept can be represented or modeled
in many different ways. For instance, subtraction can be
represented by the following symbolic model:
11 - 4
The following verbal models can also represent subtrac-
tion of these same quantities:
“Four subtracted from eleven” or
“Eleven take away four” • How many more objects left are in the larger set?

Physical models can also represent mathematical concepts. Missing Addend Model for Subtraction: 11 – 4
In these models, a number is represented by that many
objects. For example, the number 5 can be represented by • Start with 4 objects.
five pennies,squares,paper clips,tiles,or bottle caps. • Continue adding objects until a total of 11 is
reached.
• How many more objects were needed to give a total
of 11?

A physical representation of the number 5 Start:

Take-Away Model for Subtraction: 11 – 4
Continue adding objects:
• Start with 11 objects.
• Take 4 objects away.
• How many objects remain?
Group Activity
Start: Use an appropriate physical model for subtraction to solve
each of the following problems. Explain your reasoning
for choosing each model.
Take away 4:
1. Sneha has assembled 12 computer components so
far this shift. If her quota is 20 components, how
Remain:
many more components must she assemble to reach
her quota?
Comparison Model for Subtraction: 11 – 4
2. Yuko has 14 daffodil bulbs to plant in her yard. She
• Start with a set of 11 of one type of object and a set planted 5 bulbs in the front yard. How many bulbs
of 4 of another type of object. does she have left for planting in the backyard?

3. Todd is 19 years old and his sister Tanya is 13 years
old. How much older is Todd than Tanya?

Copyright 2012 Pearson Education, Inc.