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May SHPE Jr. Chapter Curriculum
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-on Activity Training
TeachEngineering Hands-on Activity:
*Estimating the Storage Capacity of a
CD/DVD
TeachEngineering Digital Library: teachengineering.org
http://www.carpelvideoonline.com/
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
TeachEngineering Digital Library
http://www.teachengineering.org
• The TeachEngineering digital library provides free,
teacher-tested, standards-based engineering
content for K-12 teachers to use in science and
math classrooms.
• Engineering lessons connect real-world experiences
with curricular content already taught in K-12
classrooms.
• Mapped to educational content standards,
TeachEngineering's comprehensive curricula are
hands-on, inexpensive, and relevant to children's
daily lives.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
General Advice
• Be prepared! Do each activity beforehand
• Make sure all materials are available
• Keep students on task
• Follow the time frame
• Be flexible
• Have Fun!!
http://commons.wikimedia.org/wiki/File:CD_DVD_Collections.jpg
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Full Activity on TeachEngineering
• Behavior of light waves, storage capacity of CDs and
DVDs
• Engineering focus:
o Engineering Research/Analysis
• Students estimate the storage capacity of CDs and DVDs by assessing
diffraction patterns of green and red laser beams.
• Students create a set up for measuring the angle of use equations
based on the diffraction of light waves to calculate data.
• Students analyze results and relate their understanding to the storage
capacity of CDs and DVDs.
• Learning objectives:
o Describe how a CD or DVD stores information.
o Explain that the laser's wavelength limits how small the pits on a CD or DVD
can be.
o Explain why a Blu-ray disc can store more information than a CD or DVD.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
• Suggested time: 30 minutes
• Suggested group size: 4 students/group
• Materials
o
o
Each group needs:
• DVD
• CD (compact disc)
• red or green laser pointer; red ones cost less than $10
each; green ones cost ~$30 each
• protractor
• small spacers to place under protractor (such as
cardboard pieces)
• plain white sheet of paper
• calculator
• Estimating Storage Capacity Worksheet, one per
student
• tape
For the instructor (optional):
• projector to show students the Estimating Storage
Capacity Presentation (optionally the 5 slides could be
printed and provided to students as a handout)
• Estimating Storage Capacity Worksheet Answers
http://www.teachengineering.org/view_activity.php?url=collection
/uoh_/activities/uoh_diffraction/uoh_diffraction_activity1.xml
http://commons.wikimedia.org/wiki/File:Dvd_cd_disk.jpg
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Engineering Connection (Real World Application):
• Optical science engineers and materials science engineers design
and create devices that satisfy the ever increasing demand for
digital storage.
• The advancement from CDs to DVDs allows more storage per disk
but also provides challenges for engineers because the physical
structures ("pits") that store data on the disks become smaller and
the CD/DVD players' lasers operate at the diffraction limit (resolution)
of light.
• In this activity, we will see how light, its interaction with matter, and
the behavior of light waves apply to our everyday lives through
engineering and technology!
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Vocabulary Terms
Definitions
angle of incidence
Angle between an incident light ray and the normal of the surface.
constructive
interference
Phenomenon in which two wavers superimpose to form a resultant
wave of greater amplitude.
diffraction grating
Optical component with a periodic structure that diffracts light into
multiple beams. Transmission diffraction gratings are lighttransmissive, like lenses; reflective diffraction gratings are lightreflecting, like mirrors.
diffraction order
Integer corresponding to a diffracted beam.
bit
Binary digit. Basic unit of information. One bit can be represented by
0/1 or on/off. Eight bites correspond to one byte.
byte
Unit of digital information. Often used with a prefix, such as MB
(megabyte) or GB (gigabyte). One byte consists of eight bits.
pit
Microscopic indentation on CD/DVD that store on bit.
pitch
Distance between two neighboring spiral tracks.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Introduction/Motivation:
o (Hold up a CD in one hand, a DVD in the other hand.) Here I have one CD and
one DVD. Can you tell which one is which? (Listen to students answers.) What is
the difference between a CD and DVD? (Answer: The amount of storage
capacity.)
o The rate of technological development is quickly increasing. Now we have Blurays, which are optical disc storage media just like CDs and DVDs, but can even
store more information. However, Blu-ray players require a blue laser. After this
activity you will understand why Blu-ray discs only work with blue lasers and not
with lasers of higher wavelengths, such as red or green lasers.
o How do we measure the size of digital data?
• Answer: Digital data is measured in bytes, which is usually used with a prefix
giga (109) or mega (106)) A byte is a unit of digital information. One byte
consists of eight bits. One bit only has two states: 0/1, which can be
regarded as on/off. All digital information is stored in the form of bits. You
can think off it as huge lines of zeros and ones. Your cell phone, computer,
TV, and iPod store your data in the form of long sequences of zeros and
ones.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Introduction/Motivation (cont.):
o CDs and DVDs store large amounts of binary data (those patterns of 0s and
1s), which a CD/DVD player can read using a laser, optical devices and
sophisticated electronics.
o CDs and DVDs are made mostly of plastic (polycarbonate) and can store
more information by having multiple recording layers. The data is stored in
a series of tiny pits, arranged in a spiral, tracking from the center of the disk
to the edge.
http://commons.wikimedia.org/wiki/File:DVD_querschnitt.svg
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Introduction/Motivation (cont.):
o The data layer is coated with a thin layer of aluminum or
silver, making it highly reflective. If stretched out, this spiral
of pits would be about 5 km long! The pit length and the
distance between pits define the digital data. The depth
of a pit is 0.11 μm and the width is 0.5 μm. Its length varies
between 0.83 and 3.56 μm.
o The spiral of pits is a periodic structure that diffracts light
into multiple beams. Such a periodic structure is called
diffraction grating. The microscopic diffraction grating is
the reason why you see beautiful rainbow colors when
white light illuminates a CD.
o When a laser beam is reflected off the disc, a diffraction
pattern is formed.
http://commons.wikimedia.org/wiki/File:DV
D_CD_pits.PNG
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Introduction/Motivation (cont.):
o The angle of incidence is the angle of the incoming laser beam with
respect to the normal of the CD surface. If the angle of incidence is
close to the normal, the condition for constructive interference is
identical to that for a transmission diffraction grating, which is given
by the following equation:
o m is the diffraction order,
o d is distance between the
rows of pits
o θ is the angular position of the
mth maximum
o The red laser has a higher
wavelength than the green
laser. You will find the
wavelength on the laser. (Red
is commonly 650nm. Green is
532nm.) Blue lasers have even
shorter wavelengths, but are
more expensive.
http://www.teachengineering.org/view_activity.php?url=collection/uoh_/activities/uoh_diffraction/uoh_diffraction_activity1.xml
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Introduction/Motivation (cont.):
o The distance between the
rows of pits, d, can be
estimated by:
d=mλ/sin(θ)
o By measuring θ and using
the given value of λ, you
can use this equation to
calculate the distance
between rows of pits.
http://www.teachengineering.org/view_activity.php?url=collection/uoh_/activities/uoh_diffraction/uoh_diffraction_activity1.xml
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Activity Procedure:
1. Have each student group use tape to attach the CD and
DVD next to each other on the edge of a table (see
image). Face the label sides away from the table. Make
sure that the centers of the CD and DVD are placed on
the table edge.
2. Place a piece of white paper on the table, and align it
along the CD.
3. Students will use the protractors to measure diffracted
laser beam angles; protractors are lifted off the table
using spacers (located at position D in image). The
spacers create a distance between the protractor and
the table, and thereby allow the laser beam to go in the
space between the sheet of paper and the protractor.
4. Remind students to make sure no one is in the path of the
diffracted laser beams, and never shine the laser pointers
in anyone's eyes!
http://www.teachengineering.org/view_activity.php?url=collection/uoh_/a
ctivities/uoh_diffraction/uoh_diffraction_activity1.xml
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Activity Procedure:
5. Have students turn on the laser pointers, and direct the
beams towards their CDs. Align the beam with the 90°
mark and the center of the protractor. The laser beam
should be aligned with the normal of the CD surface
(perpendicular to the CD). Students may need to
adjust their laser pointers slightly before seeing
diffraction patterns shown in the image.
6. When the incident and diffracted beams are clearly
visible, direct students to measure the angles of the
diffracted beams (the angle between the incident
beam and diffracted beam) and record them in their
worksheet tables. Remember that angles are
measured from the normal (the 90° mark on the
protractor). It might be easier for students to mark the
beam positions on the white sheet of paper with a
pencil and then measure the angle using their marks.
http://www.teachengineering.org/view_activity.php?url=collection/uoh_/activitie
s/uoh_diffraction/uoh_diffraction_activity1.xml
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Assessment:
o
Have students complete and hand in the Estimating Storage Capacity
Worksheets. Examine their numerical results to see how well they understood
the concepts. The results for the spacing ("d") might vary, but should be within a
reasonable range.
Activity Extension (Optional):
o
Extend the activity by varying the angle of incidence. The activity described
uses an incoming laser beam that is perpendicular to the surface (such that the
angle of incidence is zero). If the angle of incidence is not zero, the diffraction
equation from above generalizes to:
d(sin(θi)+sin(θm))=mλ
where θi is the angle of incidence. Note that if θi is set to zero, we get the
equation outlined above. In the extended activity, have students measure the
angle of incidence in addition to all other quantities described above.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Estimating the Storage Capacity of a CD/DVD
Teaching tips:
o Emphasize the science concepts, vocabulary, and engineering
connection; reinforce these throughout the activity.
o It’s important to line up the edge of the table along the diameter
of the CD. The center of the protractor should be lined up
midway between the center and the rim of the CD.
o The angles are measured from the normal. For calculations, have
students make sure their calculators are set to enter angles in
degrees.
o Emphasize the safety of lasers: Never point lasers directly towards
other people. Be especially careful not to point to lasers towards
someone's eyes.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Activity Takeaways
• Teambuilding skills
o Working together on this investigative activity, collecting data,
performing calculations and analyzing results
• Engineering skills
o Engineering Research and Analysis: gathering results, analyzing data,
relating results to real world engineering and technology that students
may use all the time.
• Encouragement through hands-on
learning
o Students learn about technology that they
may use all the time through hands-on
investigation.
• Motivation through having fun
o Introduce the activity as a fun learning
experience!
http://www.buckeyeaz.gov/index.aspx?nid=163
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
TeachEngineering Contact Information
• TeachEngineering: http://www.teachengineering.org/
o over 1,200 standards-based engineering lessons and activities
• Carleigh Samson, TeachEngineering Editor
o carleigh.samson@colorado.edu
o 303.492.6950
Questions?
http://www.fws.gov/refuge/Stone_Lakes/FAQ.html/
College Prep Activity
The Roadmap to Success
Students begin by reflecting on 6
major achievements they will
accomplish (such as taking the SAT
or getting good grades)to keep them
focused on staying on the right path
Timeline to Success
• Students create a timeline to
success and explore what
they need to do to get there.
• Students start from today
through the next school year
and reflect on major goals
they will accomplish
How to Reach My Goals
• Now that students have their
goals in mind, take a moment
to think about what they
need to do to achieve these
goals and who can help them
Soft Skills Activity
College Bound – Digital Footprint
Students learn that everything they or anyone else posts
about them online becomes part of a public online presence
known as a digital footprint.
• Students will view elements of two students’ digital
footprints and consider how the footprints might affect
those students’ admission to college.
• Students then discuss what kinds of information they
would want included in their own digital footprints, and
learn strategies for shaping a positive online presence
Closing Ceremony
SHPE Jr. Chapter Closing Ceremony
It is important to recognize the SHPE Jr. Chapter members
and their achievements during the academic year
Closing ceremony ideas
• Certificates of Participation
• Guest speakers
• Recognition of graduating seniors
• Recognition of major achievements (i.e – attended
competition, attended leadership seminars, etc.)
• Information on continued summer activities
• Group picture
Announcements
SHPE Jr. Chapter Information for 2014-2015 Form – Brief form
online to provide SHPE Foundation with SHPE Jr. Chapter contact
information for upcoming academic year (please complete by
May 30)
SHPE Scholarships are now open and accepting applications for
officially recognized SHPE Jr. Chapter members (Closing date of
May 1, 2014)
SHPE Jr. Chapter Stoles – Order forms are being accepting now.
Stoles must be ordered by May 1, 2014 or at least 3 weeks in
advance of the graduation date. Stoles only for official members
(http://www.shpefoundation.org/shpejr/)
Announcements
SHPE Jr. Chapter Summer Curriculum – SHPE
Foundation is pleased to announce we will
provide curriculum for meetings during the
summer.
Webinar trainings for summer curriculum will be
conducted once per month and include a STEM
Activity, College Prep, and Soft Skills Activity for
the months of June, July, and August.