Lesson plan: How does my iPod work?

Objectives:

  • The learner will differentiate between analog and digital data storage.
  • The learner will apply knowledge of magnets to data storage.
  • The learner will calculate data storage capacities.

Day one

Set:

Have the iPod playing in the front of the room as the class enters.

Q) Have you ever wondered how that tiny machine can remember 15,000 songs?

Q) What do you think would be the best unit to describe the space taken up by one note of one song? Would it be mm, μm, or nm?

The lesson:

A little history of recording first summarize the information on the website:

Have 2 clocks one that is analog and one that is digital.

Q) What is the major difference between the clocks?

Q) Could you tell when the time is 3:21and1/2 second? On both clocks?

Explain how 2 people could give 2 different answers for 3:21and1/2 second using the analog clock (constant sample) but both would only give 3:21 using the digital clock (until the digit changed). Relate this to the error (bad sound) when information is stored analog and clarity when digital samples are used.Hand out 1

Play a record of a song followed by a digital recording from the iPod. Make sure students note the size of the record/song vs. iPod /song. Tell them the disc in the iPod has a 1.8in diameter.

“Digital recording changes sound waves into bits (binary digits) and bytes (chunks of 8 bits) instead of groves on a record, or continuous magnetic flow on a tape.”

Q) In math when you learned about logs, did you learn about base 2?

“Digital recording uses base 2. That way you only need (only get) 2 options for each bit (binary digit) of information 0 or 1, on or off, yes or no etc.”

Have students choose one of the following activities to review or learn how to represent base 10 numbers as numbers in base 2.Briefly describe each activity to the students.

You may wish to pre-group students.(Secrete messageinvolves using ASCII and will be most appropriate for the higher level learners, they can then assist with tomorrow’s assessment activity)

Activity 1:

Supply students with a hand out and equipment neededto perform

each activity

  • Egg carton code Hand out 2
  • Birthday Bracelet Hand out 3
  • Secrete message Hand out 4
  • Binary Bank Hand out 5

Closure:

“Tomorrow I’ll ask you to use a system called ASCII to code your 1st

name as binary digits (bits).”

Day Two

Set:

Display your name in binary digits ask the students what it says.

Lesson continued:

Hand out copies of the ASCII codes.(Hand out 6)Have students write their 1st names as binary numbers using the ASCII alphabet.

Pam = 80,65,77=1010000,1000001,1001011

Q) Now that you have important bits (binary digits) of information how could magnetic domains be used to represent the bits?

Lead them to ↑ ↓ opposite domain polarity. Get them to think nano sized domains.

Q) What if we could make each bit take up only 3nm2?

Q) What would the 1st letter of your 1st name look like?

“Find someone with the same letter and see if you agree. If there is not anyone with your letter use my chart to check your work.”Hand out 8

P = ↑↓↑↓↓↓↓

Q)Now that we have a code to tell the iPod, or any hard drive, what do we do with it?

Figure 1is the inside of a hard drive, an electric signal tells the arm to fly over the disc either reading (detecting magnetic domains) or writing in (orienting domains) the magnetic film that covers the hard surface. There are often more than 1 platter (shinny disc) and arm in the hard drive. If you have the technology, use this web site to really give them a look inside the hard drive.

Figure 1

“Bottom line, if we want to make things (iPods) smaller or store more information, then we need to get more bits and bytes on to each square inch of disc space. The better the magnetic film on the disc the smaller we can go.”Highlight MRSEC research.

Put the following information on the board.

In 1990 the technology allowed 80 Megabits/in2 or .00008 Terabits/in2

Today the technology allows 200000Megabits/in2 or .2 Terabits/in2

Predictions say maybe 50000000Megabits/in2 or 50Terabits/in2

Calculate:

1. How many bits will each hard drive hold if the disc involved is 1.8 in. in diameter?

area = Π r2 bits held = capacity (bits/in2) x area (in2)

Keep track of the units you use!

2. How big does the hard drive need to be to hold 40 GigaBytes or 320 Gigabits like my iPod?

Closure: Use the iPod to play a music video, use the over head to display.