April 2010 • DynaMath • T1

TeAcher’s ediTion

April 2010Vol. 28, No. 7

ISSN 0732-7773

A SupplemeNt to Dynamath

scholastic DynaMath555 Broadway, room 474

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Are some DynaMath activities too difficult for your students? Or perhaps too easy? Go to www.scholastic.com /dynamath for differentiated repros!

This month, you get 4 leveled activities to use with pages 6–7 and 10–11, plus a PowerPoint slideshow of

the math instructions from pages 6–7 for use on interactive whiteboards.

Let us know what you think of these and other features by filling out the survey at www.scholastic.com /dynamathspring10survey. Thanks!

Digitally yours,

Matt Friedman, Editor

Differentiated repros

Content and SkillS Guidedifficulty Level: H = Easy HH = On-Level HHH = Challenging

PAGe ArTicLe TiTLe,diFFicULTY LeVeL

PriMArY MATh sKiLL sUPPLeMenTArYsKiLLs/APPLicATions

ncTM sTAndArds(see below for details)

cover Spring Into Spring! HH Working backward Computation +, 5 1, 2, 6, 8

2–3 Numbers in the News HH LcM, elapsed time Equivalent measures 1, 2, 4, 8, 9

4–5 Tigers in Trouble! HH reading a circle graph Percent of a number 1, 2, 5, 6, 8, 9

6–7 The Power of Area HH Area of a rectangle Computation 5, ÷ 1, 3, 8, 9

8–9 Wild Angles HH estimating angle measures Reading a protractor 3, 7, 8

10–11 Fantastic Fraction Foods HHH Adding frax w/unlike denoms LCD, LCM 1, 8

12–13 Count on the Census HH Analyzing data Problem solving 1, 5, 6, 7, 8, 9

14–15 What’s ART Up To? HH issue skills review Test-taking practice 1, 3, 4, 5, 6, 8

16 Derek’s the Greatest H comparing fractions LCD, LCM 1, 8

T4 Earth Angles HHH Measuring angles pp. 8–9 extension 1, 3, 4, 8

T5 Problem Solved Prep Page HH Analyzing data pp. 12–13 extension 1, 4, 7, 10

T6 Funny Franklin Fractions HH comparing fractions visually p. 16 extension 5, 7, 8

issue dates: 9/09 10/09 11–12/09 1/10 2/10 3/10 4/10 5-6/10

need Funding for DynaMath?Go to www.scholastic.com/classmags and click on Looking for Funding to learn how DynaMath qualifies for funding such as NCLB grants.

ncTM standards 1. Number and Operations 2. Algebra 3. Geometry 4. Measurement 5. Data Analysis & Probability

6. Problem Solving 7. Reasoning and Proof 8. Communication 9. Connections 10. Representation

Standards listed above in a bold box (such as 1) indicate that the article also connects with a new NCTM Curriculum Focal Point.

Your stuDents can win a DYnaMath t-shirt!Ask your students to be on the lookout for interesting events or places that they’d like DynaMath to feature in “numbers in the news.” have them send a copy of, or a Web link to, their news idea. if we use it in the magazine, they’ll win a DynaMath T-shirt. see page 2 of this issue’s student edition for details.

COVER: SPRING INTO SPRING!

STRATEGY: GRID PAPER

Have students draw three bars on

grid paper to represent the three

leaps. Let each square on the grid

represent five feet.

2–3: NUMBERS IN THE NEWS

EXTENSION: GIRAFFES . . .

Giraffe facts: There are three main

types of giraffes: the Maasai, reticu-

lated, and Rothschild giraffes. Maasai

giraffes have irregular star- shaped

markings that cover most of their

bodies. The Rothschild giraffes have

a coat that is pale and thickset when

compared with Maasai giraffes, and

the coat has less jagged patches.

Also, the area below the knee is usu-

ally unmarked.

EXTENSION: SUNNY & SPEEDY

Bonus question: About how long

would it take (in hours) to travel

1,800 miles in a car that is traveling

55 mph? (Answer: about 33 hours)

EXTENSION: BIG BASKET

Bonus question: A rectangular

basket is 10 inches long, 8 inches

wide, and 4 inches deep. How many

2-inch cubes could it hold? (Answer:

40 2-inch cubes)

4–5: TIGERS IN TROUBLE!

STRATEGY: GRAPH’S PURPOSE

Discuss the purpose of a circle

graph. Ask students why a graph is

sometimes more useful than a chart

of data. Be sure to point out that

the information about tigers on the

graph is based on estimated counts.

6–7: THE POWER OF AREA

STRATEGY: USE GRID PAPER

Have students draw each given rect-

angle on grid paper to “prove” their

calculated answer. Be certain that

students label all answers with the

correct square unit of measure.

8–9: WILD ANGLES

STRATEGY: ESTIMATION TOOL

Give each student a piece of square

note paper. Have them fold the

square diagonally. This creates a

“tool” that has a 45-degree and a

90-degree angle. Students can com-

pare the corners of this tool to each

given angle to find a reasonable esti-

mate of the measure of each angle in

the activity.

10–11: FANTASTIC . . .

STRATEGY: LCD SHORTCUTS

If two denominators are prime

numbers, multiply the two denomi-

nators. If one of the denominators

is a prime number and it is not a

factor of the other denominator,

multiply the two denominators. If

one of the denominators is a prime

number and it is a factor of the other

denominator, the greater denomi-

nator is the LCD.

14–15: WHAT’S ART UP TO?

STRATEGY: TEST TIP

Try to eliminate any answers that

you are sure are wrong, and then

make a reasonable choice from the

remaining answers.

16: DEREK’S THE GREATEST!

STRATEGY: ALTERNATE WAY

To compare the values of two frac-

tions, cross-multiply. Multiply the

numerator of the first fraction by the

denominator of the second fraction.

That is the “product” for the first

fraction. Then multiply the second

numerator by the first denominator.

That is the “product” for the second

fraction. The fraction with the great-

er “product” has the greater value.

Example: Compare 1 _ 2 with 3 _ 4 . Mul-

tiply 1 5 4. The product is 4. Then

multiply 2 5 3. The product is 6.

Therefore, 3 _ 4 is greater than 1 _ 2 . (Why

this works: In cross-multiplication,

you are actually taking a shortcut

to finding fractions with a common

denominator by simply multiply-

ing both denominators together. In

the example 1 _ 2 compared with 3 _ 4 , we

could find a common denominator

by multiplying 2 and 4. The com-

mon denominator would be 8. Then

to find the numerator for 3 _ 4 , we also

must multiply 3 by 2 as we did with

its denominator. To find the numer-

ator for 1 _ 2 , we must multiply the 1 by

4, as we did with its denominator. )

—Dale Beltzner

Mr. Beltzner is the Math Subject Area

Leader for the Southern Lehigh School

District in Bethlehem, Pennsylvania.

Lesson plans

T2 • DynaMath • April 2010

TEACHERS: Make one copy per student, or assign one problem each day to start your math lesson!

Prob

lem

of

the

Day

Try

one

of t

hese

qui

ck e

xerc

ises

eac

h da

y as

a f

ast,

fun

way

to

star

t yo

ur m

ath

less

on!

Nam

e __

____

____

____

____

____

____

____

____

____

SK

ILL

S P

AG

E

Problem of the Day by Dale Beltzner. Scholastic Inc. grants teachers permission to reproduce this page. © 2010 by Scholastic. All rights reserved.

April 2010 • DynaMath • T3

DA

Y 1

M

ultipl

y m

e by

2, a

nd

the

prod

uct

is le

ss

than

13.

Div

ide

me

by

4, a

nd t

he r

emai

nder

is

1. I

’m n

ot 1

. Wha

t nu

mbe

r am

I?

DA

Y 6

M

y te

nths

pla

ce is

twic

e m

y te

ns. M

y on

es p

lace

is

1 _ 2 my

tent

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is

2. Fi

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my

dig

its:

__

___

____

_ . _

____

DA

Y 1

1 A

re t

here

mor

e

even

-num

ber

ed

day

s or

odd-n

umber

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day

s in

Apri

l?

DA

Y 1

6

Sam

my

pul

led a

n

Apri

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ol’s

pra

nk

and r

emov

ed a

ll th

e od

d d

igit

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om t

he

face

of

a cl

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W

hat

dig

its

wer

e le

ft?

DA

Y 2

The

LC

M o

f tw

o nu

mber

s is

36. The

diffe

renc

e bet

wee

n th

e nu

mber

s is

3. W

hat

are

the

two

num

ber

s?

DA

Y 7

Fi

ll in

the

nex

t tw

o item

s in

thi

s pa

tter

n:

11, 2

, 15,

3, 2

1, 4

, 29,

__

_, _

__

DA

Y 1

2

Whi

ch let

ter

in t

his

wor

d d

oes

not

have

a

line

of s

ymm

etry

? M

AT

HE

MA

TIC

AL

DA

Y 1

7

Use

the

dig

its

9, 4

, 6,

and 6

to

crea

te t

wo

equi

vale

nt f

ract

ions

. Eac

h dig

it m

ay b

e us

ed

only

onc

e.

DA

Y 3

W

hat

is t

he v

alue

of

n in

thi

s eq

uati

on?

n

n

+ 1

= 6

5

DA

Y 8

W

hat

two-

dig

it p

rim

e nu

mber

has

a s

um o

f it

s dig

its

that

is

not

7,

but

is

a m

ulti

ple

of

7?

DA

Y 1

3

Mul

tiply

a n

umber

by

itse

lf. T

hen

div

ide

the

pro

duc

t by

2. Yo

ur f

inal

an

swer

is

18. W

hat

was

th

e or

igin

al n

umber

?

DA

Y 4

The

top

spe

ed o

f La

ura’

s so

lar-

pow

ered

ca

r is

80

mile

s pe

r ho

ur. H

ow far

can

th

e ca

r tr

avel

in 1

5

min

utes

?

DA

Y 9

W

hat

num

ber

am

I?

✔ I h

ave

3 diffe

rent

dig

its,

all

of t

hem

odd.

✔ D

igit

s ar

e in

ord

er

from

lea

st t

o gr

eate

st.

✔ E

venl

y div

isib

le b

y 5.

DA

Y 1

4

It r

aine

d for

5 d

ays.

Eac

h day

, 1 __

4 in

ch o

f ra

in

fell.

How

muc

h ra

in fel

l in

all

dur

ing

the

5 d

ays?

W

rite

you

r an

swer

as

a m

ixed

num

ber

.

DA

Y 1

9

The

nam

es o

f 3

girl

s an

d 4

boy

s ar

e pla

ced

in a

hat

. W

hat

is t

he

pro

babili

ty o

f dra

win

g th

e na

me

of t

he

talle

st p

erso

n?

DA

Y 5

U

se t

he d

igits

1, 2

, 4,

7, a

nd 9

onc

e ea

ch t

o cr

eate

the

num

ber

w

ith

the

grea

test

val

ue.

No

odd

digi

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an s

it

side

by

side

.

DA

Y 1

0

Joey

wen

t fish

ing.

H

e ca

ught

3 f

ish

bef

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noon

and

2 f

ish

afte

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on. H

e ca

ught

6 f

ish

in a

ll. H

ow c

an

this

be?

DA

Y 1

5

Whi

ch u

nit

of m

easu

re

doe

sn’t

bel

ong?

Why

?

liter

qu

art

kilo

gram

pi

nt DA

Y 2

0

Buz

z ta

kes

in 2

,50

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calo

ries

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s.

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w m

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105-c

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as

equa

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cal

orie

s?

Da

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8

At

wha

t ti

me

of d

ay

(a.m

. or

p.m

.) is

th

e pro

duc

t of

the

ho

urs

and m

inut

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121?

Name______________________________________

Earth Angles2Recycling one aluminum can saves enough

energy to keep a TV on for ______ minutes!

3Americans use about ______ billion bottles of water per year—even though most tap water

is perfectly healthy.

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Extension Activity

T4 • DynaMath • April 2010

Using a Protractor to MeasUre angles4 Place the center mark at the bottom of the protractor on the vertex (point) of the angle. 4 Line up the 0-degree (º) line of the protractor with one ray of the angle. 4 Look at the number on the protractor that aligns with the other ray of the angle. (You may need to extend the ray.)4 Be sure to read the correct number. Acute angles are less than 90°. Right angles are exactly 90°. Obtuse angles are greater than 90°.

1Save water by taking fewer baths and more showers. A full bathtub requires ______ gallons

of water. A 5-minute shower uses about 50 gallons less than that!

4 Measure the angle that appears after the sentence. 3 Write the angle measure without the degrees symbol in the box provided. 4 That number completes the Earth-friendly fact.

What to Do

What can you do to help the planet? Measure angles to find out!

4 If 1 _ 4  of the food Americans throw away is saved instead, ______ million hungry people

could be fed each day.

5Use both sides of a piece of paper! Every year, each American uses the amount of

paper that comes from one ______-foot-tall Douglas fir tree.

Name______________________________________

Problem Solved Prep Page Analyze Data

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Warm-Up Activity

For question 1: Find the box in the chart where the “Population 5 to 14 years old” row meets the “Steepest Hills” column.

FOR QUESTION 2: Think: What row of the chart do you need to look at to compare the three towns’ total populations?

FOR QUESTION 3: Think: Which age range listed on the chart includes 16- to 30-year-olds? And which town has the greatest population in that age range?

FOR QUESTION 4: Think: Which row of the chart is most important to look at?

FOR QUESTION 5 and supermath: Try to think through each of these problems on your own!

On pages 12 and 13, we ask you to analyze data to help make sense of the U.S. Census. Below, we give one way you can think about each question from those pages. Remember: There isn’t always just one

way to think about the data. But your answer does need to make sense. That means you need to be able to explain why you chose the answer that you did.

What to DoUse the information below to help you think

about each question on pages 12 and 13.

April 2010 • DynaMath • T5

Name______________________________________

Funny Franklin Fractions

1. 5 __ 8  _____7 __   O >  A <

2. 7 __ 9 _____ 

3 

__ 4  K >  P <

3. 2 _ 5 _____ 3 __ 4  R >  S <

4. 6 __ 7 _____

5 __ 6  N >  Y <

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Extension Activity

T6 • DynaMath • April 2010

5. 7 __ 9 _____ 

4 

__ 5    D >  C <

6. 3 __ 8 _____

4 __ 9  L >  H <

7. 3 _ 5  _____5 __ 6   E >  G <

8. 11 __ 12 _____

4 __ 5    I >  T <

WhatmightBenjaminFranklinhavesaidaboutflyingakiteduringalightningstorm?

“IT WAS A 

3   6   1   5   2   8   4   7

EXPERIENCE!”

4Ineachproblem,comparethefractionsbyshadinginthefractionalpartofeachbar.Thefractionbarthatisfilledinmoreisgreater.4Circlethecorrectsymbol,<or>,andwriteitintheblankbetweenthenumbers.4Atthebottomrightofthepage,writetheletterthatisnexttothecorrectsymbolintheblankabovethenumberoftheproblem.Whenalltheblanksarefilled,you’llgettheanswertoourjokeaboutBenjaminFranklin.

What to Do

7 __ 12 

3 __ 4 

3 __ 4 

5 __ 6 

4 __ 5 

4 __ 9 

5 __ 6 

4 __ 5