dominant sep: dominant ccc: management strategies to

Strand: 8.2.6

Emphasis: Analog and digital signals

Anticipated Time Required: LE 1 - 30 minutes LE 2 - 30-45 minutes LE 3 - 75-90 minutes LE 4 - 30-45 minutes

Dominant CCC: Structure and function

Dominant SEP: Engaging in argument from evidence; communicating information

Management Strategies to support equitable access to content: My Favorite No (celebrating wrong answers and using them to develop deeper understanding)

Shopping list: Learning episode 2: Tuning forks (an assortment of frequencies; ideally enough for each group of 3 students to have at least to forks, but 1 for each group or even one set to use for a class demonstration will work)

E. Harward

8.2

.6 D

igit

al

ver

sus

An

alo

g S

ign

als

Sto

ryli

ne

An

chor

Ph

eno

men

on

: N

AS

A h

as s

ent

sig

nals

out

into

spac

e, w

ith i

mpo

rtan

t in

form

atio

n t

hat

co

uld

be

rece

ived

by e

xtr

ater

rest

rial

life

, if

it

exis

ts.

Big

Qu

esti

on

: W

hat

types

of

sig

nals

are

bes

t su

ited

fo

r st

ori

ng a

nd t

ransm

itti

ng i

mpo

rtan

t in

form

atio

n?

Stu

den

t P

erfo

rman

ce E

xp

ecta

tion

:

8.2

.6:

Obta

in a

nd e

valu

ate

info

rmat

ion t

o c

om

mu

nic

ate

the

claim

that

the

stru

cture

of

dig

ital

sig

nals

are

a m

ore

rel

iable

way t

o s

tore

or

tran

smit

info

rmat

ion t

han a

nalo

g s

ignals

. E

mp

hasi

ze t

he

basi

c under

stan

din

g t

hat

wav

es c

an b

e use

d f

or

com

mu

nic

atio

n p

urp

ose

s. E

xam

ple

s co

uld

inclu

de

usi

ng v

inyl re

cord

vs.

dig

ital so

ng f

iles,

fil

m c

am

eras

vs.

dig

ital

cam

eras,

or

alco

ho

l th

erm

om

eter

s vs.

dig

ital th

erm

om

eter

s.

NG

SS

Evid

ence

Sta

tem

ents

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om

inan

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EP

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gy

Str

uct

ure

and f

unct

ion

A

rgu

ing f

rom

evid

ence

; co

mm

unic

atin

g

info

rmat

ion

S

cien

ce E

xp

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Wh

at

are

stu

den

ts d

oin

g?

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is s

hou

ld m

atc

h y

ou

r

SE

P!)

Wh

at

spec

ific

un

der

stan

din

gs

shou

ld s

tud

ents

get

fro

m t

his

exp

eri

ence?

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qu

esti

on

s st

ud

ents

have

to p

rop

el u

s to

th

e

nex

t sc

ien

ce e

xp

eri

ence

.

Ass

ess

men

t

1

CC

C:

Cau

se

and e

ffect

;

stru

cture

and

funct

ion

SE

P:

Arg

uin

g

fro

m e

vid

ence

Tim

efr

am

e:

20 m

inute

s

Stu

den

ts m

odel tr

ansm

issi

on

of

dif

fere

nt

sig

nals

.

So

me

sig

nals

are

mo

re d

isto

rted

than

oth

ers

duri

ng t

ransm

issi

on.

Ho

w d

oes

a s

ound s

ignal

get

fro

m t

he

sourc

e to

the

targ

et?

What

co

uld

cau

se

dis

tort

ions

in s

ound

wav

es?

Fo

rmat

ive:

Stu

den

t ex

pla

nat

ions

and

suppo

rtin

g e

vid

ence

of

whic

h s

ignals

to u

se i

n w

hic

h

situ

atio

ns

can b

e use

d t

o

asse

ss t

heir

under

stan

din

g o

f

the

dif

fere

nt

types

of

sig

nals

mo

dele

d b

y t

he

cla

ss.

E. Harward

https://www.nextgenscience.org/sites/default/files/evidence_statement/black_white/MS-PS4-3%20Evidence%20Statements%20June%202015%20asterisks.pdf

https://www.nextgenscience.org/sites/default/files/evidence_statement/black_white/MS-PS4-3%20Evidence%20Statements%20June%202015%20asterisks.pdf

2

CC

C:

Ener

gy

and m

atte

r;

cause

and

eff

ect

SE

P:

Dev

elo

pin

g

and u

sing

mo

dels

Tim

efr

am

e:

30 m

inute

s

Stu

den

ts u

se o

bse

rvat

ions

fro

m a

tunin

g f

ork

to

cre

ate

a

mo

del to

sho

w h

ow

so

und

wav

es

tran

sfer

ener

gy f

rom

one

pla

ce t

o a

noth

er.

So

und e

ner

gy i

s tr

ansf

erre

d

thro

ugh t

he

air

vis

lo

ng

itud

inal

wav

es

(stu

den

ts d

o n

ot

nee

d t

o

kno

w t

he

term

, but

sho

uld

under

stan

d t

he

conce

pt)

Ho

w c

an w

e re

cord

and

sto

re t

hes

e w

aves

if w

e

wan

t to

sen

d a

sig

nal

far

away o

r to

the

futu

re?

Fo

rmat

ive:

Stu

den

t m

odels

of

sound

wav

es

are

use

d t

o a

sses

s

their

under

stan

din

g o

f ho

w

sound e

ner

gy i

s tr

ansf

erre

d.

3

CC

C:

Str

uct

ure

and

funct

ion;

cause

and

eff

ect

SE

P:

Co

nst

ruct

ing

exp

lanat

ions

Tim

efr

am

e:

75-9

0 m

inute

s

Stu

den

ts s

end a

nalo

g a

nd

dig

ital

sig

nals

, an

d c

om

par

e

the

resu

ltin

g i

nfo

rmat

ion t

o

the

ori

gin

al

info

rmat

ion.

They

com

par

e th

ese

sig

nals

to

the

sig

nals

mo

dele

d d

uri

ng t

he

tele

pho

ne

gam

e in

the

firs

t

less

on.

Stu

den

ts r

ead a

bo

ut

the

dif

fere

nces

bet

wee

n a

nalo

g

and d

igit

al w

aves.

They

obse

rve

and c

om

par

e an

alo

g

and d

igit

al au

dio

sig

nals

, and

evalu

ate

ho

w w

ell t

he

inte

gri

ty o

f th

e si

gnals

are

main

tain

ed d

uri

ng s

tora

ge

and

tran

smis

sio

n.

Analo

g s

ignals

are

eas

ily

dis

tort

ed,

and b

eco

me

mo

re

dis

tort

ed e

ach t

ime

they a

re

tran

smit

ted.

Dig

ital

sig

nals

can b

e m

ore

easi

ly t

ransm

itte

d w

itho

ut

bec

om

ing d

isto

rted

.

Dig

ital

sig

nals

only

inclu

de

a

sam

ple

of

the

ori

gin

al

sound

ener

gy.

The

stru

cture

of

dig

ital si

gnals

allo

ws

them

to

be

sto

red i

n

small

er s

pac

es f

or

longer

tim

es

wit

ho

ut

bec

om

ing c

orr

upt,

but

the

sounds

are

som

ewhat

sim

pli

fied

.

The

stru

cture

of

analo

g s

ignals

mak

es

it p

oss

ible

to c

aptu

re

richer

so

unds,

bec

ause

all

of

the

sound i

s re

cord

ed,

but

they t

ake

mo

re s

pac

e to

sto

re a

nd c

an b

e

Whic

h t

ype

of

wave

sho

uld

we

use

to

sto

re

and t

ransm

it s

ignals

?

Fo

rmat

ive:

Stu

den

t an

alo

gie

s o

f

dig

ital/

analo

g s

ignals

and t

he

sig

nals

sent

duri

ng t

he

tele

pho

ne

gam

e sh

ou

ld b

e

use

d t

o a

sses

s th

eir

under

stan

din

g o

f th

e benefi

ts

and d

raw

bac

ks

of

each t

ype

of

sig

nal (d

igit

al and a

nalo

g).

E. Harward

corr

upte

d (

by h

eat

, bac

kgro

und

no

ise

duri

ng r

eco

rdin

g,

etc.

).

4

CC

C:

stru

cture

and

funct

ion

SE

P:

Engag

e in

arg

um

ent

fro

m e

vid

ence

Tim

efr

am

e:

30-4

5 m

inute

s

Stu

den

ts g

ather

/rev

iew

info

rmat

ion a

bo

ut

dig

ital

and

analo

g s

ignals

fro

m a

sho

rt

vid

eo,

and t

hen

use

evid

ence

to s

upport

a c

laim

that

answ

ers

the

ques

tio

n,

“Sho

uld

we

use

analo

g o

r dig

ital

sig

nals

to

sto

re a

nd t

ransm

it

impo

rtan

t in

form

atio

n f

or

the

futu

re?”

Dig

ital

and a

nalo

g s

ignals

bo

th

have

benefi

ts a

nd d

raw

back

s.

S

um

mat

ive

:

Stu

den

ts s

ho

uld

wri

te a

n

argu

menta

tive

essa

y u

sing

evid

ence

to s

uppo

rt t

he

cla

im

that

eit

her

analo

g o

r dig

ital

is

bet

ter

for

sto

ring a

nd

tran

smit

ting s

ignals

bas

ed o

n

stru

cture

and f

unct

ion.

Use

the

rubri

c to

identi

fy

excell

ent

studen

t pap

ers.

E. Harward

8.2.6 Learning Episode 1

Student Science Performance

Topic: Digital vs. Analog Title: Telephone Game Activity

Overarching Performance Expectations (Standard) from State Standards or NGSS: Obtain and evaluate information to communicate the claim that the structure of digital signals are a more reliable way to store or transmit information than analog signals. Emphasize the basic understanding that waves can be used for communication purposes. Examples could include using vinyl record vs. digital song files, film cameras vs. digital cameras, or alcohol thermometers vs. digital thermometers.

Lesson Performance Expectations: Students should model transmission of different types of signals, and should use evidence to explain how the structure of the signals affect their functions

CCC: Structure and function; cause and effect SEP: Asking Questions; developing models

Students Will. . . To Construct Meaning Engage with a phenomenon: Sometimes information is changed when it is transmitted from a source to a target. Starter: Signals are used to transmit information from one place to another, or from one time to sometime in the future. Complete the 3-2-1 activity in your lab book:

● 3: types of signals that could be used to transmit information

● 2: things that all signals have in common

● 1: question that you have about signals Gather: As a class, you will be modeling two different types of signals. We’re going to compare the information that gets sent to the information that is received, and decide which type of signal would be better for transmitting information. Follow your teacher’s instructions for modeling the transmission of signals.

Teacher Will. . . To Support Students Give the students the starter. As they work on the questions, circulate through the room and make note of what students are writing. If there are specific ideas that you want students to share during the class discussion, quietly tell the students you’ll be calling on them during the discussion so they are prepared. After students complete the starter, facilitate a class discussion. Some ideas that you should help students bring out:

● Signals could be visual (waving at a friend, signaling with mirrors or smoke, etc.), auditory (whales singing to each other, yelling or laughing, etc.), etc.

● All signals contain information and have a starting point (source) and a target; the information signals contain could be very different (How is the information communicated by a smile different from the information communicated by someone poking you? What about the difference in information between a wave or rolling your eyes?)

Allow students to share some of their questions about signals, but at this point, don’t answer any of them. Tell students that we will be trying to figure out answers to some of their questions over the course of this unit. Post the questions and refer to them throughout the unit when appropriate. For the first signal: You will be playing the telephone game. Prepare a card that is labeled “signal 1” and write the sentence you would like to communicate on it. Have students stand in a line or a circle. The last student has a blank card labeled “signal 1.” Show your card with the sentence on it to the first student. She should then whisper the message to the next student, who whispers it to the next student and so forth until the last student receives the message. When the last student receives the message, she records it on the card and hands the

E. Harward

Reason: With your group, discuss which signal would be better for transmitting information. To record your ideas, make a table in your lab book and record the pros and cons of each signal we modeled. Communicate: Determine which of the signals you would want to use for each of the following. In your lab book, record which signal you would use and why:

● Send a short message during a natural disaster

card to you. For the second signal: Prepare a card that has a series of dots and is labeled “signal 2.” Each student should have a blank card and a pencil. Students should be standing in a line, so they are facing the back of the person that they will be transmitting the signal to. Hand your card to the first student. She will then tap the shoulder of the next student, and show him the card. After looking at the card, he will turn back around, record the message on his own blank card, and tap the shoulder of the next student. This process is repeated until the last student has recorded the message. Collect the card from the last student, label it “signal 2,” and allow everyone to return to their seats. Note: if you have a large class, consider breaking them into two groups for this activity to save time. You can start the message at the beginning of each line and collect the ending cards from each line. Make sure that you use the same number of groups for both signals. Once students return to their seats, display the starting and ending messages from each signal. Place students in small groups to discuss the differences in the two signals. As they discuss and record their ideas, circulate through the class and listen to what they are saying. Facilitate a class discussion to allow students to explain the benefits and drawbacks of each type of signal. Some ideas students may have:

● Signal 1 con = message was distorted/information was changed during the signal transmission

● Signal 2 con = dots don’t really mean anything/no useful information was transmitted

● Signal 2 pro = message wasn’t as distorted At some point, help focus student attention on the structure of the signals. For example, signal 1 contained a lot of information, but was easily distorted. Use questions to bring out the fact that signal 2 would need to be translated into something meaningful. You could give the example of Morse code, where letters are translated to symbols at the source (dashes and dots), and the target would have to translate the symbols back into letters to make the signal meaningful. The simple structure of the signal make it easier to transmit without distortion, but the information was not necessarily useful. Later in the unit, students will need to understand that digital signals need to be turned back into analog signals for us to hear and make sense of them. Helping students understand that translating information to a different form that can be transmitted with fewer distortions and then translated back into something meaningful will set up a good foundation for later lessons. Have students determine which signal would be better in each situation and record their ideas in their lab books or use as an exit ticket. There is not a correct answer to which signal is better, but students should be able to explain why they would use one signal over the other.

E. Harward

● Tell your friend why you didn’t go toher birthday party

When students are done, introduce the anchor phenomenon by briefly telling them that different organizations, including NASA, have sent signals out into space to transmit information to other lifeforms, if they exist. During this unit, students will be working to determine what types of signals would be best suited for storing and transmitting important information.

Assessment of Student Learning Student responses should include evidence to support their choice of which signal is better in each situation; examples include:

● “Signal 2 would be better in a natural disaster because there could be large consequences if the informationbeing transmitted was changed; for example, if you were trying to communicate your location to a rescuer andthe information was changed, they wouldn’t be able to find you.”

● “Signal 1 would be better for talking to your friend, because he wouldn’t have to translate the dots. If there was alot of information because you had a long excuse, your friend would have to translate a lot of dots. Plus, if youare telling your friend directly, the information doesn’t have as much chance to become distorted.”

Telephone Game Start and End Card Examples

E. Harward

Signal 1 Source

The funny bunny hid the colored candy in the car.

Signal 1 Target

Signal 2 Source

⚫⚫⚫ ⚫

Signal 2 Target

Name _______________________________________________________________ period _______

E. Harward

3-2-1 Starter Signals 3 types of signals that could be used to transmit information:

★

★

★

2 things that all signals have in common:

★

★

1 question that you have about signals:

★ Name _______________________________________________________________ period _______

E. Harward

Signals Exit Ticket

Which signaling method would you want to use in each of the following situations? Why?

Situation Which signal would you use?

Explain your answer.

You need to send a short message during a natural disaster

You need to tell your friend why you didn’t go to his birthday party

Name __________________________________________________________________ period _________

Signals With your group, discuss the benefits and drawbacks of each of the signals we modeled in class. Record your ideas in the table below.

Pros Cons

Signal 1

Signal 2

E. Harward



Topic: Digital vs. Analog Title: Modeling a Wave


Lesson Performance Expectations: Students will use observations to develop a model to show how sound energy is transferred from the source to the target.

CCC: Energy and matter; cause and effect SEP: Developing and using models

Students Will. . . To Construct Meaning Engage with a Phenomenon: When you hit a tuning fork against the table, the forks vibrate and it makes a noise. Gather: With your group, investigate and observe the tuning forks. In your lab book, record your ideas about:

● How are the tuning forks transmitting signals?

● What information is transmitted in the signals coming from the tuning forks?

● Are the tuning forks transmitting the same information? Is there a way to change the information being transmitted by the tuning forks?

Reason: You will be developing a model to show how a signal was sent from the tuning fork to your ear. To do this, start by defining the system:

● Where are the system boundaries? For example, is the system just the fork and the air directly around the fork? Does it include the entire school?

● What are the parts of the system? For example, is the hand holding the tuning fork part of the system? What about your ear? What about your hair? Is there any empty space in the system?

● Describe the function of the different parts of the system. How is the structure of each part related to its

Teacher Will. . . To Support Students

Note: This is a great episode to find ways to connect to previous storylines regarding energy transfer and movement of matter. Ideally, you could provide each group of 3 students with 2-3 tuning forks to play with. If this is not practical for your budget, consider giving each group one tuning fork to start with and allowing them to trade with other groups throughout the activity. As a last resort, you could demonstrate a few tuning forks for the class to observe. Provide a sheet with the investigation questions or display the questions on the board. As students investigate and discuss with their groups, circulate through the class and use questions to help students clarify their ideas. If your students are familiar with developing models, you can quickly remind them of the factors they need to consider (defining the system, including energy flow, and thinking about how to actually represent these ideas). If your students are not as practiced at making models or need extra scaffolding, take a few minutes on each step. Review systems, and allow students a few minutes to write down their system boundaries and the parts of the system before moving on to energy. After reviewing systems, energy and features that models can include, allow students time to revise their models. As they do this, circulate through the room. If there are students who need additional guidance, use questions to help them think through the processes happening in the system and how they want to represent these processes. Example questions:

● “What was going on with your ear that allowed you to hear the signal? Did the tuning fork have to touch your ear?”

● “What fills the space between the fork and your ear? Does

E. Harward

function? For example, what is the structure of the tuning fork? What is its function? How are the structure and function related?

Now think about the energy in the system: ● What forms of energy are present in the

system? ● What is the energy doing? Is it stored?

Is it flowing? ● Is the energy causing any changes to

the system? If so, what are they? Now revise your model to show how a signal is sent (and received!) in the system. You may want to think about what type of features will be useful for your model:

● Zoom-in boxes? ● Before-during-after diagrams? ● Written descriptions/explanations? ● Key?

During the class discussion, you are welcome to add notes to your model. You will be revising your modes, and can refer to the notes you take. After watching the sound wave simulation, revise your model. Make sure it shows how the sound energy travels through the air.

this play a role in transmitting the signal?” ● “Did the signal only go to your ear, or did it hit other targets

as well? How can you show this in your model?” ● “What could you actually see happening? What are parts of

the system that you didn’t actually see, but are making a guess about what was happening?”

● “How does the structure of _____ affect its function?” ● “What would happen if the tuning fork’s structure was

different? What if it was made out of glass? Could it still have the same function? Why or why not?”

Allow students a few minutes to share their models with their partners. If needed, model what their discussion should look and sound like, and consider setting a timer so students know when to switch roles. As students discuss, circulate through the room and listen to their ideas. Identify students who have ideas that will help facilitate a class discussion, specifically listening for ideas about how the sound energy is able to move through the air. Selecting students who have both correct and incorrect ideas about this to participate in the class discussion will provide an opportunity for all students to think about how the sound travels through the air.

Management Strategy: Eavesdropping on student discussions is an important skill! As you listen to students and identify ideas that will help facilitate the class discussion, tell the students that you will be calling on them during the discussion. For many students, knowing when they will be called on and already having an idea prepared allows them to participate in the class discussion without as much anxiety. Also consider telling the student why you want him to share his idea:

● “I’ve never had a student come up with that idea! I’d love for everyone to hear it.”

● “You worded your idea so well. I want to make sure the rest of the students have a chance to write it down.”

● “You two have such different ideas, and you both made great arguments to support your ideas. I love the way you listened to each other, even though you don’t agree. I’m going to call on you first during the class discussion to share your ideas.”

Facilitate a class discussion to allow students to share their ideas. During the discussion, build a class model (or several, if needed) to show the students’ ideas of how sound travels through the air. If the class understands how sound waves affect air molecules as they travel from the fork to your ear, allow students to revise their own models. If the class has come up with several ideas about how sound waves travel, use the “soundwaves” simulation at https://musiclab.chromeexperiments.com/Sound-Waves to allow

E. Harward

https://musiclab.chromeexperiments.com/Sound-Waves

Communicate: Share one revision you made to your model with your partner.

● Show your partner the revision (“I added _____.” or “I changed _____.” or “I got rid of _____.”)

● Tell your partner why you made the revision (“Before I thought _____, but now I know _____, so I changed it to ______.” or “I realized my model didn’t show _____, so I _____.”

students to see how air molecules are affected as sound energy passes through them. At this point, do NOT click on the magnifying lense in the simulation! Although it lets you zoom-in and see the molecules better, it traces the path of a single molecule in a way that creates a transverse wave on the screen, and students could come away with the misconception that this is what sound waves look like as they travel through the air. After playing with the simulation (and discussing the observations that students make), allow the students time to revise their drawings. If needed, remind students that zoom-in boxes and before-during-after sequences might be useful in showing how the air molecules move as sound energy is transmitted through the air. Give students 1-2 minutes to share their revisions with their partner.

Assessment of Student Learnings Student models should be used to assess their understanding of how sound signals can be transported through the air from a source to their ear. Models should include:

● System parts/boundaries ● Representation of energy moving from the fork outward ● Representation of the effects on the air molecules as the sound waves pass through them (how the energy

causes them to move) ● Zoom-in boxes, written descriptions, etc. that effectively communicate the student’s ideas.

Example:

Name ______________________________________________________________ period _______

E. Harward

Tuning Forks As you play with the tuning forks, record your observations and ideas about the following. You can use words and pictures to record your ideas.

How are the tuning forks transmitting signals? What information is transmitted in the signals coming from the tuning forks?

Are all of the tuning forks transmitting the same information? Is there a way to change the information being transmitted by the tuning forks?

Before creating your model, write down your ideas about the following:

What is the system? What are the system boundaries, and what are

the parts of the system?

What form(s) of energy are in the system? What is the energy

doing? Is it stored? Is it causing changes?

What are some features that you could include to communicate your

ideas?

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Topic: Digital vs. Analog Title: Analog and digital signals


Lesson Performance Expectations: Students analyze and interpret visual representations of sound waves, and use evidence gathered from reading to determine if the sound waves were transmitted using analog or digital technologies.

CCC: Patterns; structure and function SEP: Analyzing and interpreting data; arguing from evidence

Students Will. . . To Construct Meaning

Engage with a phenomenon: Visual representations of sound waves show that some sound recordings change when repeatedly transmitted while other recordings do not.

Gather: You will be playing the telephone game again, but this time you will be using different signals.

After you play the game and listen to the final messages, respond to the following questions in your lab book:

● Compare this telephone gameto the first one we played.What was the same? Whatwas different? Which signalswere analogous?

● What forms of energy wereinvolved? Was theinformation passed fromperson to person in the typeof sound wave we modeledlast time with the tuningforks? If not, how was theinformation passed fromperson to person?


Note: The opening activity requires students to have electronic devices that can record sounds; some students will also need to send texts or emails. If you choose to have students use their cell phones for the activity, consider putting them in groups so that those who do not have or do not want to use their phones for the activity are paired with someone who has a phone. Classroom chromebooks, tablets, etc. give every student equal access and are a great option for this; however, it might take longer for students to figure out how to send and receive the message. If at all possible, don’t skip this activity because it will be engaging to your students and set up a great foundation for the rest of the lesson.

If you have time and resources, allow the students play the telephone game again, only this time use actual digital and analog signals (students do not need to know those terms at this point). Divide the class into two groups. Have one student from each group bring their phone or computer out in the hall with you. Each student should use the microphone on their computer to record the same message from you (say the message one time, with both students recording; you may want to check and make sure both students recorded the entire message). Return to the class with the students, and explain that they each have the same recording of a message from you on their phone/computer. One team has to actually play and re-record the message each time they pass it from one person to the next. The other team can send the audio file by email or text; they should not actually open the file and listen to it. After the message has been passed through each team, the whole class can listen to the final version of each message.

After students have a chance to respond to the questions in their lab books, facilitate a short class discussion to allow them to share their ideas. At this point, don’t feed them information. Just listen and use what they are saying to assess their understanding of signals and sound waves, and also to identify misconceptions.

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Individually, read the information regarding digital and analog signals. As you read, underline the pros and cons of digital signals and the pros and cons of analog signals. Make a small note next to each underlined statement to show what type of signal it is talking about and if you think it is a pro or a con. Reason: With your partner, determine which signal from the first telephone game was a model of digital signals and which was a model of analog signals. Also determine which signal from today’s telephone game was a digital signal and with was analog. Your answer should include information regarding the structure of the signals. Record your ideas, and make sure you include evidence from the reading to support your answers! You are welcome to use words and pictures in your explanation. Look for patterns in the waves you see on the screen and the noises that produced the waves. What are the effects of:

● changing the volume of the sound?

● changing the pitch of the sound?

● singing, clapping your hands or whistling?

● one person talking vs. three people talking?

The pictures are visual representations of sound waves. The

Distribute the readings. As the students read, circulate through the room and observe the statements that they are underlining. Remind students to note if each statement is a pro or a con. Consider providing ELL/SPED students with an abbreviated version of the reading (included with the lesson materials). This video may also be used to help students differentiate between digital and analog; consider starting it at 0:12ish (a word that may offend some students is displayed at the beginning of the video): https://www.youtube.com/watch?v=btgAUdbj85E. If needed, use small group or a whole group discussion to let students share the pros and cons they found in the reading. Tell students that during the first telephone activity, they modeled the transmission of digital and analog signals. During the telephone activity they did for this lesson, they actually used digital and analog transmissions. Tell students that their task is to use evidence from the reading to determine which signal was digital and which was analog (and which signal modeled digital and which modeled analog). As students work with their partners, circulate through the room and listen to their ideas. If needed, remind students that they need to record their own claim about how each signal was modeled, and include evidence. Use questions to help students clarify their ideas. Encourage students to look at the notes they made during the telephone activity. Listen for student ideas that will be helpful in facilitating the class discussion. Facilitate a short class discussion to allow students to share their claims and evidence. Evidences that students may use to support their claims:

● Digital signals must be converted from analog, then converted back to analog for us to hear them

● Analog signals contain more information than digital, because they contain all of the sounds and digital signals only contain samples

● Digital signals take up less storage space than analog signals Introduce the students to the idea that we can use a tool called an oscilloscope to visualize sound waves. Two great simulators that you can demonstrate for the class (project your computer screen; your computer will need a microphone so students can record sounds):

● https://academo.org/demos/virtual-oscilloscope/ ● https://musiclab.chromeexperiments.com/Voice-Spinner (this allows

you to see the sound waves and play them back at different speeds; students don’t need to understand how the frequency affects sound, but students will like playing around with it and will be able to see the visual representation of a sound wave)

Record a few sounds as a class and reiterate that these are not actual sound waves, but are visual representations of the waves. If needed, remind students of the sound wave models they created, and point out the differences, including the way sound waves affect the air molecules and do not move in the up-and-down pattern of the waves in this simulations. Distribute the sound wave transmission pictures and allow students time with their partner to analyze and interpret the pictures. If individual accountability is

E. Harward

https://academo.org/demos/virtual-oscilloscope/

https://www.youtube.com/watch?v=btgAUdbj85E

https://musiclab.chromeexperiments.com/Voice-Spinner

original sound wave was transmitted five times using one type of technology. Then the original sound wave was transmitted five times using a different type of technology. With your partner, look at the visual representations of the waves, and predict which final transmission sounded most like the original. Be ready to explain and support your answer during the class discussion. Communicate: Review the signal pictures. One transmission was digital and the other was analog. Which do you think was digital? Write your answer on your card, and include the evidence or reasoning you used to support your answer. When you finish, give your card to your teacher.

needed for a particular class, ask students to write down which signaling method maintained the integrity of the sound and include their evidence. Otherwise, have students discuss these ideas and be ready to share during the class discussion. Facilitate a short class discussion to allow students to share their ideas. Before moving to the next section, ensure that students understand the difference between analog and digital signals, and that they understand the pros and cons of each. During the discussion, if students make claims that one signal was digital and the other was analog, don’t tell them if they are right or wrong, but do ask them to share their evidence and reasoning with the class. Distribute an index card or slip of paper to each student. Tell the students that the original signal was transmitted using digital technology and that the original was transmitted using analog technology. They must determine which signal was transmitted digitally. Students should write their answer, including their evidence/reasoning, on the slip of paper and hand it in. Once all responses have been collected, use the My Favorite No strategy to help students further analyze the question.

Formative Assessment Strategy: My Favorite No from http://www.redesignu.org/design-lab/learning-activities/my-favorite-no **Although this strategy can be very effective for helping students develop deeper understanding of a concept and reinforce the idea that wrong answers are a part of learning, it can be ineffective if used in a class that does not have a “failing forward” culture! Be sensitive about how you use this strategy. If used frequently in the right climate, it can help establish norms of having wrong answers and then working to correct them. After collecting student responses, sort them into two piles: a “yes” pile that contains correct answers and a “no” pile that contains incorrect answers. Say “yes” and “no” as you do this so students can see how you are sorting the answers. As you sort the answers, look for common mistakes that students are making, or for answers that include misconceptions that will be useful in helping students analyze the concept. Select the “no” answer that will help facilitate a discussion that will allow students to come to a deeper understanding of the concept. In this case, the “no” answer might include the correct signal, but have incorrect evidence/reasoning to support it. Tell the class that this is your favorite no answer, and make it clear that this answer is incorrect. (Do not identify who wrote the answer!) Read the answer to the class and ask them to analyze it by:

● determining which parts of the answer are correct ● which parts are incorrect, what makes these parts incorrect, and what

changes could be made to make the answer correct End on a positive note! Acknowledge that it can be difficult to have your wrong answer analyzed by the class, even when it is done anonymously and remind the students the importance of wrong answers.

Assessment of Student Learning Written responses and ideas shared during partner and class discussions should be used to assess how well students understand differences between analog and digital signals. Student responses should demonstrate that they understand:

● Digital signals are less likely to become corrupted with repeated transmission and can be stored in a smaller

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http://www.redesignu.org/design-lab/learning-activities/my-favorite-no

space; to make a digital recording, only samples of the original soundwave are recorded ● Analog signals are more likely to become corrupted and take more space to store, but analog technologies record

the complete soundwave

Digital and Analog Signals

E. Harward

When analog technology is used to record a sound, every part of the sound wave is recorded. The recorded sound waves

can be very complex, because the recording device records every sound that it picks up, even background noises that are

traveling through the air. The pictures to the right are visual representations of sounds that were recorded using analog

technology.

These signals can be changed easily, because when the sound is transmitted and recorded, it is hard for every part of the

wave to be recorded exactly the same each time.

Any additional background noise could be recorded

with it, changing the wave and the sound.

When sounds are recorded digitally, not

every part of the sound wave is recorded.

Instead, the recording device takes samples

of the sound wave, and assigns it to be either “on” or “off.” The picture to the right shows the recording of a digital wave.

One thing you might notice is that in the analog recording, the wave can have any value. There are points of the wave at

0.2, -1, 1.4, etc. If the wave is recorded digitally, there are only two values. The wave can either be at 0 or 1. Since there

are only two options for any point on the wave, it is harder to make changes to the wave if the sound is transmitted. Since

the wave retains the same values, the sound it encodes remains unchanged.

To make a digital recording, the sound has to be translated into a simpler version. The information takes up less storage

space and is less likely to get changed or altered. However, to be able to get any information from the signal, it must be

converted back into an analog signal before being transmitted to your ears.


These pictures shows sounds that were recorded

with analog technology.

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These sound waves are complex. This makes it hard to keep the sound waves exactly the same when they are copied.

If these sound waves are copied, there will probably be small changes to them. This will change the sounds.

This picture shows a sound that was recorded with digital technology.

These waves are simpler. It is easier to copy

these waves without changing them. This

means that the waves can be copied or

stored without changing the sound.

Digital signals do not take as much space to

store as analog signals. This is why you can store many songs in your phone or computer. Before you can listen to this

sound, it must be changed from a digital wave to an analog wave.

Transmission A

Original sound wave

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Sound wave after being transmitted five times

Transmission B

Original sound wave

Sound wave after being transmitted five times

Name __________________________________________________________________ period ________


Which signal (1 or 2) from the telephone activity at the beginning of the unit modeled a digital signal? What evidence can you use to support your answer? Remember to discuss the structure of the signals!

E. Harward

Which signal (1 or 2) from the telephone activity at the beginning of the unit modeled an analog signal? What evidence can you use to support your answer? Remember to discuss the structure of the signals!

Which final transmission (A or B) sounded more like the original? What evidence do you have to support your answer?

E. Harward



Topic: Digital vs. Analog Title: Which signal should we use?


Lesson Performance Expectations: Students will use evidence about the structure of digital and analog signals to support an argument about which type of signal we should use to store and transmit information.

CCC: Structure and function SEP: Engage in argument based on evidence; communicate information

Students Will. . . To Construct Meaning

Engage with a Phenomenon: Digital recordings maintain the same structure when recorded and transmitted. Analog recordings capture the sound as it originally was, without altering the sound waves.

Gather: You will be making a claim about digital and analog signals. If you feel like you need more time to make sense of this information, use the tools your teacher has provided.

Reason: What are the pros and cons of sending all that information in analog form to a target far away and in the future? How does the structure of analog signals relate to the pros and cons on your lists? Record your ideas in your lab book.


Use the formative assessments you made during the previous lesson to determine how much additional information and sense-making opportunities your students need before they will be able to successfully make an argument regarding how we should store and transmit signals. If students need additional support, consider:

● Having them create a diagram to show how digital and analog signals are similar and different

● Allowing them to gather information about digital and analog signals from various sources, and recording information about the signals in a graphic organizer

● Developing a model to show what happens to the sound energy if they sing into their phone’s voice recorder, text the song to a friend, and the friend listens to it; students should show the difference between the analog waves and the digital waves

Sources that might be helpful for students to continue gathering information:

● https://www.youtube.com/watch?v=btgAUdbj85E (same video link as the previous lesson; consider starting the video at 0:12 to avoid showing a word that could be offensive to some students)

● http://www.cyberphysics.co.uk/topics/waves/analogueanddigital.htm (fairly short and straight-forward article about digital and analog signals)

● https://www.cliffsnotes.com/cliffsnotes/subjects/math/what-s-the-difference-between-digital-and-analog (short article about digital and analog signals)

Introduce students to the golden record: NASA recorded sounds and images using analog technology and sent them into space on Voyager on what is called “the golden record.” A brief description of the record can be found at https://voyager.jpl.nasa.gov/spacecraft/goldenrec.html. You can listen to sounds from the golden record on soundcloud (if you do a search for “NASA

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https://www.cliffsnotes.com/cliffsnotes/subjects/math/what-s-the-difference-between-digital-and-analog

http://www.cyberphysics.co.uk/topics/waves/analogueanddigital.htm

https://www.youtube.com/watch?v=btgAUdbj85E

https://voyager.jpl.nasa.gov/spacecraft/goldenrec.html

https://www.cliffsnotes.com/cliffsnotes/subjects/math/what-s-the-difference-between-digital-and-analog

Communicate: You will need to make a claim that answers the question, “What type of signal should we use to store and transmit important information?”

● Record your claim.● Record evidence to support

your claim.● Explain your reasoning; how

does the evidence you listedsupport your claim?

golden record” in https://soundcloud.com/, you’ll find several different playlists; here is one: https://soundcloud.com/nasa/sets/golden-record-sounds-of). Students may find it interesting that we’ve actually used analog technology to store and transmit information to a target far away and far into the future. Play some of the recordings for the students, and let them comment of the quality of the sounds and the possible benefits of sending signals into space in analog form.

Allow students time to record their pros and cons; consider asking students to do this in partners or small groups. It is important that they understand of the benefits and the drawbacks of using analog signals before they start on their final assessment.

Consider giving students the choice to develop an explanatory model to communicate their claim, evidence and reasoning, or to use the traditional written form. The same rubric can be provided regardless of the format the student selects. Provide students with the question. Depending on the class, you may want to provide additional scaffolding by giving students a graphic organizer to record their claim, evidence and reasoning, and then allow them to use these notes on their final product. You could also consider walking through each piece with the class. To do this:

● Go over the question with the class.● Remind students that the claim is a statement that answers the question,

and give them a minute to write their claim.● Remind students that evidence is the stuff we observe. If needed,

provide an example piece of evidence, and then allow students time torecord the evidence that supports their claim. Encourage students tolook at their previous notes as they do this.

● Explain to students that their reasoning is where they explain how theevidence they listed supports the claim they made. Allow students towork on their reasoning.

Remember that constructing their reasoning using evidence is hard for students and they need a lot of practice. If you have a large number of ELL/SPED or struggling students, of if the claim-evidence-reasoning process is new to your students, consider providing additional scaffolding. Some ideas are included in the teacher materials for this lesson.

In this case, students are using the claim-evidence-reasoning model to generate notes they can use to produce either an argumentative essay or model to communicate their claim and support it with evidence.

Assessment of Student Learning Students pro/con lists should be used to formatively assess their understanding of the differences between analog and digital signals. Students should have a good grasp of these differences before they are asked to do the summative assessment.

Student CERs should be used as a summative assessment; a suggested rubric is below. Although students can choose to claim that analog technologies are better for storing information, somewhere (either in their formative or summative assessments), they should recognize that information is less likely to become corrupted if stored digitally.

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https://soundcloud.com/

https://soundcloud.com/nasa/sets/golden-record-sounds-of

Surpasses proficiency

● Student claim is relevant ● At least three pieces of relevant evidence are used to support the claim ● Explanation of how or why the evidence supports the claim is included and relevant ● Student ideas and understanding are communicated effectively (for example, symbols used

in models are clear or written responses are structured in a way that makes the student explanation easy to follow)

● Counterclaims are included and addressed

Proficient ● Student claim is relevant ● At least two pieces of relevant evidence are used to support the claim ● Explanation of how or why the evidence supports the claim is included and relevant ● Student ideas and understanding are communicated effectively (for example, symbols used

in models are clear or written responses are structured in a way that makes the student explanation easy to follow)

Approaching proficiency

● Student claim is relevant ● At least one piece of relevant evidence are used to support the claim ● Explanation of how or why the evidence supports the claim is included; some pieces may

be incomplete or irrelevant ● Student ideas and understanding are mostly communicated effectively; there may be some

pieces that are hard to interpret or ambiguous

Below proficiency

● Student claim may be irrelevant or missing ● Evidence cited is not relevant ● Explanation of how or why the evidence supports the claim may be missing, incorrect or

incomplete ● Student ideas and understanding are not communicated effectively; it may be hard to

understand the student’s ideas

Examples of proficient products:

We should use digital technology to store and transmit signals, especially if we are trying to store or send important information. Digital signals take less space than analog signals. When we played the telephone game, the digital signal took much less space on the card than the analog signal. Even though this was just a model, it represents how much space each type of signal takes up. If we have a lot of important information to store, it will be easier to fit it all in if the information is digital. Digital signals also sound more like the original, no matter how many times you transmit them. When we looked at the images of the sound, the image of the sound after it was transmitted digitally looked almost identical to the original, but the signal that was transmitted with analog technology looked very different from the original. This shows that when the signals are transmitted, the analog transmission changes the signal. If the information that we want to transmit is important, we should store it digitally so it doesn’t get changed. Since digital signals sound more like the original. even after a long time, and they take less space to store, we should use digital signals to store and send important information.

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E. Harward

Claim, Evidence, Reasoning Scaffolding Ideas Note: Students may be familiar with the term “argument” from writing arguments in their ELA classes. In many science lessons and teaching resources, the “reasoning” section is similar to the argument used in ELA. In the claim-evidence-reasoning (often referred to as CER or Cl-Ev-R) model, the reasoning section is where students construct an explanation for how or why the evidence they cited supports their claim. Differentiating between the evidence and reasoning is difficult for students and takes practice. The evidence consists of the data they collected and/or the observations they made, while the reasoning is an explanation of how or why the data supports the claim. In this case, students will be using evidences collected during class activities and discussions, as well as from readings. Simply listing the data is not enough to support a claim. In the reasoning section, students must describe how the different pieces of evidence can be linked together to support the claim. The first few times students do a CER, they will need some scaffolding. Three different levels of scaffolding are included below, with level III providing the most scaffolding.

Level I: Provide students with possible claims and allow them to select the claim they have the most evidence to support. They can then use the evidence they generated to construct their argument. Possible claims:

● We should use digital signals to store and transmit important information● We should use analog signals to store and transmit important information

Additionally, sentence stems could be provided to help students write their reasoning. This could be particularly helpful to ELL students.

Level II: Provide students with claims and evidences; allow them to determine which pieces of evidence could support each claim. Sometimes there may be evidences could be used to support multiple claims, or students may have evidence to support more than one claim. After determining which evidences support which claims, students select one claim and use the evidence to construct their argument. You could provide these in a list and allow students to draw lines from the evidence to the claim that it supports, or cut them into strips that students can sort. Possible claims/evidence:

Claims Evidences

● We should use digital signals tostore and transmit importantinformation

● We should use analog signals tostore and transmit importantinformation

● The dot signal was transmitted with only one mistake● The spoken signal was changed so much that it didn’t

contain the same information at the end● Sound waves cause air molecules to bump into each other● When an analog signal is first recorded, it contains all of

the information from the source● When a digital signal is first recorded, it contains samples

of the information from the source● Digital signals take less space than analog signals● Background noise cannot interfere with a digital signal

while it is being transmitted● Background noise can interfere with an analog signal

while it is being transmitted

Level III: Provide students with only one claim and a list of evidences (these could be from the examples in the table above). Students determine which of the evidences could be used to support the claim, and then use the evidences they selected to write their reasoning. If additional scaffolding is needed:

● Students could be given the claim and the evidence to support it, and then asked to write their reasoning. In thiscase, students would be responsible to explain why/how the evidence provided supports the claim given to them.

● Sentence stems could be provided to help students write their reasoning; this may be particularly helpful for ELLstudents.

E. Harward

Name _______________________________________________________ period ________

Analog vs. Digital

What are the pros and cons of using each type of signal to store and transmit information? How does the structure of each type of signal contribute to its benefits and drawbacks?

Pros Cons

Analog

Digital

Question: What type of signal should we use to store and transmit important information?

Claim:

Evidence Reasoning

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dominant sep: dominant ccc: management strategies to

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