# 1 materials Objectives Teaching the Lesson

```Objectives
To describe general number patterns in words; and
to write special cases for general number patterns.
1
materials
Teaching the Lesson
Key Activities
Students describe a general number pattern in words and write examples or special
cases of it. They are given special cases for a general pattern and describe it with a
number sentence having one variable.
Math Journal 1, pp. 82–84
Student Reference Book, p. 105
calculator
Key Concepts and Skills
• Apply a general pattern to find 10% of a number.
[Number and Numeration Goal 2]
• Extend numeric patterns.
[Patterns, Functions, and Algebra Goal 2]
• Write a number sentence containing a variable to describe a general pattern.
[Patterns, Functions, and Algebra Goal 1]
• Apply general patterns to explore multiplicative and additive inverses.
[Patterns, Functions, and Algebra Goal 4]
Key Vocabulary
general pattern • variable • special case
Ongoing Assessment: Informing Instruction See page 182.
2
materials
Ongoing Learning & Practice
Students practice and maintain skills through Math Boxes and Study Link activities.
Ongoing Assessment: Recognizing Student Achievement Use journal page 85.
[Patterns, Functions, and Algebra Goal 1]
3
materials
Differentiation Options
Students use the “What’s
My Rule?” routine to relate
general number patterns
and special cases.
Math Journal 1, p. 85
Study Link Master (Math Masters,
p. 74)
calculator
ENRICHMENT
EXTRA PRACTICE
Students describe patterns
and relationships among
triangular numbers, square
numbers, and rectangular
numbers.
Students write rules to
describe numeric patterns.
Teaching Masters (Math Masters,
pp. 71–73)
5-Minute Math, pp.158, 240,
and 242
Technology
Assessment Management System
Math Boxes, Problem 2
See the iTLG.
180
Unit 3 Variables, Formulas, and Graphs
Getting Started
Mental Math and Reflexes
Math Message
Students rename mixed numbers and whole numbers
as fractions. Suggestions:
1. Write the number that is the opposite of
a. 15 15 b. 8 8 c. d. 0 0
a. 5 5 0
b. 2.6 2.6 0
c. (11) (11) 0 d. y (y) 0
1 5
14 4
1 33
8 4 4
1 22
37 7
2 8
2 3 3
5
5 1
64
64 1
e. (x) x
1 Teaching the Lesson
Math Message Follow-Up
WHOLE-CLASS
DISCUSSION
Have students share their answers. Pose additional problems, if
necessary. Suggestions:
7
7
●
What is the opposite of 8? 8
●
What is the sum of any number and its opposite? 0
ELL
To review the concept of opposites, have students refer to page 105
in the Student Reference Book. Most students are familiar with opposite in
relation to position; as in opposite sides of a rectangle are congruent. Draw a
number line on the board and show the positional relationship between a number
and its opposite to zero. Model the sum of any number and its opposite on the
number line.
A U D I T O R Y
K I N E S T H E T I C
T A C T I L E
Student Page
V I S U A L
Date
LESSON
3 1
Describing General Number
PARTNER
ACTIVITY
Patterns with Variables
(Math Journal 1, pp. 82 and 83)
Time
Patterns and Variables
103
Study the number sentences at the right. All three sentences
show the same general pattern.
10
10% of 50 100 50
10
10% of 200 100 200
This general pattern may be described in words: To find 10%
10
1
of a number, multiply the number by 100 (or 0.10, or 10 ).
10
10% of 8 100 8
The pattern may also be described by a number sentence
0
that contains a variable: 10% of n 1
n.
100
A variable is a symbol, such as n, x, A, or
. A variable can stand for any one of
many possible numeric values in a number sentence.
10
10
Number sentences like 10% of 50 100 50 and 10% of 200 100 200 are
0
examples, or special cases, for the general pattern described by 10% of n 1
n.
100
Read and discuss the text at the top of journal page 82. Have
students complete Problem 1 and discuss their solutions. Be sure
to cover the following points:
To write a special case for a general pattern, replace the variable with a number.
Example:
General pattern
10% of n 10 n
Special case
10% of 35 10 35
100
100
1. Here are 3 special cases
for a general pattern.
Rules that describe patterns are sometimes called general
patterns.
10
10
1
725
725
1
2
1
1
1
2
a. Describe the pattern in words.
Any number divided by itself equals 1.
b. Give 2 other special cases for the pattern.
9
9
A general pattern may be described in words.
1
50
0
500
1
2. Here are 3 special cases
A general numeric pattern may be described with symbols, at
least one of which represents a number. Symbols that represent
numbers are called variables.
A variable can have any one of many possible numeric values.
A common misunderstanding of variables is that a variable
always stands for one particular number.
for another general pattern.
15 (15) 0
3 (3) 0
1
4
1
(4) 0
a. Describe the pattern in words.
Any number added to its opposite equals zero.
b. Give 2 other special cases for the pattern.
0.75 (0.75) 0
100 (100) 0
82
Math Journal 1, p. 82
Lesson 3 1
181
Student Page
Date
Time
LESSON
Patterns and Variables
3 1
continued
When a particular number is substituted for the variable in a
general pattern, the result is called an example, or a special
case, of the general pattern.
103
3. A spider has 8 legs. The general pattern is: s spiders have s 8 legs.
22 8 176 legs
Write 2 special cases for the general pattern.
10 8 80 legs
a.
b.
There are many ways to describe the same pattern using
n
b
variables. For example, n 1, b 1, and
1 all describe
the pattern in Problem 1 on journal page 82.
4. Study the following special cases for a general pattern.
6
The value of 6 quarters is 4 dollars.
10
The value of 10 quarters is 4 dollars.
33
The value of 33 quarters is 4 dollars.
a. Describe the general pattern in words.
The value of n quarters is n4 dollars.
To support English language learners, discuss the everyday
meaning of variable and of special case, as well as their
meanings in this context.
b. Give 2 other special cases for the pattern.
The value of 15 quarters is 145 dollars.
100
The value of 100 quarters is 4 dollars.
Write 3 special cases for each general pattern.
5. p p 2 p
6. c 1
c 1
7. p p (3 p) 5 p
8. s s (s 1) s
4 4 2 4
1.8 1.8 2 1.8
20 20 2 20
Have partners complete journal pages 82 and 83. They may
use calculators.
1
2 2 1
33 313 1
1
6.4 6.4 1
NOTE There are no actual calculations required on these pages, but some
2
52 5 (5 1) 5
102 10 (10 1) 10
92 9 (9 1) 9
2 2 (3 2) 5 2
3.8 3.8 (3 3.8) 5 3.8
16 16 (3 16) 5 16
students may want to verify that a particular number sentence is true. This may
) .
involve the use of parentheses keys (
When most students have completed the journal pages, ask
volunteers to share their solutions.
83
Math Journal 1, p. 83
NOTE General patterns may be described
in words or by an open number sentence.
Whenever Everyday Mathematics asks
students to write a general pattern, they
should write a number sentence that describes
the pattern, unless the directions specifically
state that they are to describe it in words.
Time
LESSON
3 1
Writing General Patterns
103
Following is a method for finding the general pattern for a group
of special cases.
8 /1 8
0.3 / 1 0.3
Solution Strategy
Step 1 Write everything that is the same for all of the special cases.
Use blanks for the parts that change.
/ 1
Each special case has division by 1 and an equal sign.
Step 2 Fill in the blanks. Each special case has a different number, but the number is
the same for both blanks, so use the same variable in both blanks.
Possible solutions:
N
/1
N
, or
x
/1
x
/1
, or
1. 18 1 18
2.75 1 2.75
6
10
6
1 10
2. If a nonzero number is divided by itself, the result is equal to 1.
A general pattern that is written with a variable looks the same as
any of the special cases for that pattern. The only difference is
that the variable has been replaced by a specific value.
(See margin.)
PARTNER
ACTIVITY
with Number Sentences
(Math Journal 1, p. 84)
12.5 / 1 12.5
Example: Write the general pattern for the special cases at the right.
Write a general pattern for each group of 3 special cases.
1. If the numerator and denominator of a fraction are the same
number (except 0), the fraction is equivalent to 1.
Describing General Patterns
Student Page
Date
Have students describe each general pattern in their own words
before giving special cases for the pattern. There is often more
than one way to describe a pattern in words. Two ways of
n
describing the general pattern n 1 follow.
General pattern
x 1x
General pattern
T 00
General pattern
c cats have c 4 legs
As a class, read and discuss the problem and solution strategy at
the top of journal page 84. Ask students to decide which parts stay
the same in all of the special cases and which parts change from
case to case.
Circulate and assist as needed. When most students have
completed the page, ask volunteers to share their solutions.
2. 6 0 0
1
2
00
78.7 0 0
Ongoing Assessment: Informing Instruction
3. 1 cat has 1 4 legs.
2 cats have 2 4 legs.
5 cats have 5 4 legs.
4. 6 6 6
1
2
2
1
1 2
2 (2)
0.7 0.7 (0.7)2
General pattern
2
84
Math Journal 1, p. 84
182
Unit 3 Variables, Formulas, and Graphs
Watch for students who do not recognize what the special cases have in
common. Some students may benefit from circling all the numbers and symbols
that stay the same from one special case to the next.
Student Page
Date
2 Ongoing Learning & Practice
Time
LESSON
Math Boxes
3 1
1. Complete the “What’s My Rule?” table.
2. Write 3 special cases for the
general pattern.
Rule: Subtract 1.32
Math Boxes 3 1
INDEPENDENT
ACTIVITY
in
out
8
6.68
0.83
0.48
2.15
1.8
(Math Journal 1, p. 85)
4.89
7.33
Mixed Practice Math Boxes in this lesson are paired with
Math Boxes in Lesson 3-3. The skills in Problems 5 and 6
preview Unit 4 content.
Writing/Reasoning Have students write a response to the following:
Explain how you know where to place the decimal point in the
quotient of Problem 4. Sample answer: I estimated. 90 divided by
6 is 15, so 93.6 divided by 6 is about 15.
Math Boxes
Problem 2
3.57
6.01
32 33
253
103
3. Write each number in number-and-word
4. Divide.
notation.
.6
69
93
a. 200,000
200 thousand, or 0.2 million
b. 16,900,000,000
16.9 billion
c. 58,400,000,000,000
58.4 trillion
1
4
a. 7
7
42–45
6. Compare each pair of fractions.
5
7
Write < or >.
3
a. 10
5
9
10
3
7
c. 11
11
11
1
5
6
d. 1 15.6
93.6 6 5. Add or subtract.
7
b. 9
Ongoing Assessment:
Recognizing Student Achievement
a (b + c) (a b) + (a c)
1 (2 3)(1 2) (1 3)
5 (10 5) (5 10) (5 5)
7 (20 9)(7 20) (7 9)
2
9
83
b. 100
4
c. 15
19
d. 20
6
5
10
81
100
5
15
20
20
83
75
85
Use Math Boxes, Problem 2 to assess students’ ability to write special cases
for a general pattern. Students are making adequate progress if they are able to
write three special cases. Some students may recognize the general pattern as
illustrative of the Distributive Property of Multiplication over Addition.
Math Journal 1, p. 85
[Patterns, Functions, and Algebra Goal 1]
Study Link 3 1
INDEPENDENT
ACTIVITY
(Math Masters, p. 74)
Home Connection Students practice describing general
patterns with words and number sentences having one
variable. They write special cases for general patterns.
Teaching Master
Name
Date
7
8
43 0 43
36.09 0 36.09
(2 24) 24 3 24
100 0.25 0.25 100
0.5 0.25 0.25 0.5
For each set of special cases, write a general pattern.
7 0.1 7
10
52 53 55
3 0.1 3
10
132 133 135
4 0.1 5.
6.
3
10. 4
100
75
1 00
12
11
16
21
7
20
25
60
20
2.
110
300
Add 5 to the in number.
Rule:
out
4
100
Divide the in number by 3.
You are writing special cases for a general number pattern
when you complete a “What’s My Rule?” table.
s 0.1 Rule: Add the opposite of the number.
(x x 0)
m0 1
Rule: Divide by the number.
(y y 1)
out
in
out
3
0
8
1
25
0
0
0
9
1
1
1
53
1
4
100
Use the values from the table above to write special cases for the following
general number patterns:
x x 0.
y y 1.
Special cases
Special cases
Complete.
in
13
7
1
(2)0 1
s
10
Practice
10
out
8
in
20 1
1460 1
4
10
x2 x3 x5
1
7. 10
103, 253
Complete.
s 0.25 0.25 s
32 33 35
in
Rule:
(2 10) 10 3 10
General Patterns and Special Cases
You are describing a general number pattern for a special case
when you write a rule for a “What’s My Rule?” table.
105
(2 m) m 3 m
Time
Write a rule for each table shown below.
52 0 52
For each general pattern, give 2 special cases.
4.
1.
103
7
8
0
Give 2 other special cases for the pattern.
b.
3.
Describe the general pattern in words. Sample answers:
The sum of any number and 0 is equal to the original
number.
a.
2.
3 1
Following are 3 special cases representing a general pattern.
17 0 17
Date
LESSON
Variables in Number Patterns
31
1.
Name
Time
0.10
0.75
1
8. 4
4
11. 5
25
—
— 0.
—
25
1
9. 5
80
7
12. 10
100
80
100
Math Masters, p. 74
0.
20
100
70
100
0.20
0.
70
Example: 3 3 0
Example: 8 8 1
25 25 0
7 7 0
53 53 0
9 9 1
1
1
1
4
4
100 100 1
Math Masters, p. 71
Lesson 3 1
183
Teaching Master
Name
Date
LESSON
Time
3 Differentiation Options
Number Patterns
31
Triangular, square, and rectangular numbers are examples of number patterns
that can be shown by geometric arrangements of dots. Study the number
patterns shown below.
Triangular Numbers
Square Numbers
1st
2nd
3rd
4th
1st
2nd
3rd
4th
Rectangular Numbers
Connecting General Number
INDEPENDENT
ACTIVITY
5–15 Min
Patterns and Special Cases
(Math Masters, p. 71)
1st
1.
2nd
3rd
4th
Use the number patterns to complete the table.
Number of Dots in Arrangement
2.
1st
2nd
3rd
4th
Triangular
Number
1
3
6
10
15 21 28 36 45 55
Square
Number
1
4
9
16
25 36 49 64 81 100
Rectangular
Number
2
6
12
20
30 42 56 72 90 110
What is the 11th triangular number?
5th
6th
7th
8th
9th
10th
To provide experience with algebraic notation, have
students use the “What’s My Rule?” routine. By
completing “What’s My Rule?” tables, some students may
more easily make the connection between general number
patterns and special cases in Part 1 of this lesson.
66
How does the 11th triangular number compare to the 10th triangular number?
It is 11 more than the 10th triangular number.
ENRICHMENT
Exploring Number Patterns
Math Masters, p. 72
PARTNER
ACTIVITY
5–15 Min
(Math Masters, pp. 72 and 73)
To apply students’ understanding of general patterns, have
them work with a partner to discover some relationships among
figurate numbers—special numbers associated with geometric
figures. For example, the sum of two successive triangular
numbers is a square number; and the sum of a rectangular
number and its corresponding square number is
a triangular number.
EXTRA PRACTICE
5-Minute Math
Teaching Master
Name
Date
LESSON
31
3.
Number Patterns
Time
continued
Describe what you notice about the sum of 2 triangular numbers that
are next to each other in the table.
Sample answer: The sum is a square number.
4.
Add the second square number and the second rectangular number; the
third square number and the third rectangular number. What do you notice
about the sum of a square number and its corresponding rectangular number?
The sum is a triangular number.
5.
Describe any other patterns you notice.
Sample answer: Rectangular numbers are twice
the corresponding triangular numbers.
6.
You can write triangular numbers as the sum of 4 triangular numbers when repetitions
are allowed. For example: 6 1 1 1 3
Find 3 other triangular numbers that can be written as sums of exactly
4 triangular numbers.
10 1 3 3 3
15 3
3
3
6
21 3
6
6
6
Math Masters, p. 73
184
Unit 3 Variables, Formulas, and Graphs
SMALL-GROUP
ACTIVITY
5–15 Min
To offer more practice extending and describing numeric patterns,
see 5-Minute Math, pages 157, 240, and 242.
```