Transcript SHPE Foundation Noche de Ciencias Hands

SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-on Activity Training
TeachEngineering Hands-on
Activity:
*Light Intensity Lab
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TeachEngineering Digital
Library:
teachengineering.org
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!!
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SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
Full Activity on TeachEngineering
• Light intensity, light attenuation
• Engineering focus:
o Engineering Research/Analysis
• Perform an experiment to observe the
relationship between light intensity and
attenuation layers.
• Develop a rule (equation) based on empirical
data that can be used in future applications.
• Learning objectives:
o Derive the relationship between light intensity and
the number of layers of attenuation.
o Perform experiments to illustrate the concept of
attenuation.
http://www.nibib.nih.gov/science-education/science-topics/x-rays
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
• Suggested time: 50 minutes
• Suggested group size: 3 students/group
• Materials (per group):
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lamp
Incandescent 60W bulb (not halogen)
12” x 12” piece of aluminum foil
clean transparencies
printed light intensity scale (print each one,
photocopies may not show the correct
grayscale detail)
12” masking tape
scissors
Access to Excel or a graphing calculator
Light Experiment Handout (student version)
• For the instructor:
• Light Experiment Handout (teacher version)
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SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
Engineering Connection (Real World Application):
• Light attenuation and Beer's Law are engineering concepts
that are very important for many engineers.
• Environmental engineers use this concept when building
solar panels as a means of alternative energy.
• NASA has used the concept of attenuation (with radio
waves) to determine information about Saturn’s rings.
• Biomedical engineers use these concepts in the design of xray machines, and also in other broader applications such
as the field of biomaterials.
o In this activity, measuring bone mineral density using xray machines is used as the motivation engineering
connection for the experiment.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
Vocabulary Terms
Beer’s Law
Definitions/Equations
Beer’s Law relates how much light is absorbed by a material it is
passing through to properties of that material. More specifically, Beer’s
Law calculates the number of photons striking a detector (N) based on
the number of incident photons (N0). For the case of an x-ray:
𝑁 = 𝑁0 𝑒 (𝜇𝑠 𝜇𝑏𝑀𝑠𝑀𝑏 )
where μs and μb represent the mass attenuation coefficients (cm2/g) of
soft tissue and bone (respectively) and Ms and Mb represent the area
densities (g/cm2) of the two tissue types.
Light Attenuation
Light Intensity
The loss of light intensity as light passes through a material. The extent
of attenuation is based on the light entering the material and properties
of the material.
𝐼 = 𝐼0 𝑒 −𝜇𝑙
where I = light intensity, I0 = light intensity when light does not pass
through any medium, μ = attenuation coefficient (based on material
light passes through and light energy), l = path length of the light
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
Activity Procedure:
Before the Activity:
o Make sure each group is able to work at a table pushed up against a wall
to shine the lamp onto and take intensity measurements (limit the group
numbers/ increase the group size if necessary).
o Experiments must be performed with the room lights turned off and the
shades drawn – only using light from the lamps.
o Make copies of the worksheet for each group.
o Set out materials at each work station.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
Activity Procedure:
With the Students:
o Tape the light intensity scale to the wall just above the
surface of the table, and set up the lamp to shine on the
scale (do not turn on the lamp yet).
o Cut the transparency into eight equal-sized pieces.
o Take a piece of foil and cut a 5 mm diameter hole in the
center of it.
o Next, cover the face of the lamp by wrapping the
aluminum foil around it, making sure that the hole is in the
center of the face of the lamp and that the foil does not
cover the vents in the back of the lamp.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
Activity Procedure (cont.):
o Darken the room, turn on the lamp, and hold a piece of
transparency a couple inches from the wall to cast a
shadow near the scale (but not on the scale).
o Match the intensity of the resulting shadow on the wall with
a square on the scale. (Note: It’s easier to distinguish the
matching shade of gray if you step back to look at it.)
o Record the intensity in Table 1 on the first page of the
worksheet.
o Repeat the process with two sheets of transparency
stacked together, then three, and so on until the table is
filled.
o Use Excel to plot the natural logarithm of the shadow’s
intensity versus the thickness of the attenuator. (Instructions
provided on the worksheet – if computers are not
available, have students use graphing calculators and
graphing paper to create this graph.)
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
Sample Results
Thickness =
Number of
Transparencies
Light Intensity
Natural Log of
Intensity =
ln(intensity)
Ln(Intensity) vs. Thickness
4.65
100
4.605170186
1
96
4.564348191
2
90
4.49980967
3
88
4.477336814
4
84
4.430816799
5
81
4.394449155
6
78
4.356708827
7
77
4.343805422
4.6
y = -0.0385x + 4.5937
R2 = 0.9834
4.55
Ln(Intensity)
0
4.5
4.45
4.4
4.35
4.3
0
2
4
Thickness (# of sheets)
6
8
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Light Intensity Lab
Teaching tips:
o Emphasize the science concepts, vocabulary, and engineering
connection; reinforce these throughout the activity.
o Ask students if they have ever had an X-ray. Explain that the
concepts explored in this activity are what allowed engineers to
develop X-ray technology! Ask them if they think they would have
healed from injuries as well if doctors were not able to use X-rays.
o Once students have made their graphs, discuss the results as a
class. Ask students if they discovered a relationship between the
layers of attenuation (layers of transparencies) and the light
intensity. Ask them what this suggests about light (or x-rays)
passing through dense materials versus less dense materials.
o Have fun and encourage students to have fun!!
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Activity Takeaways
• Teambuilding skills
o Making decisions, sharing tasks and materials
• Engineering skills
o Engineering Analysis: performing an experiment, taking quantitative
measurements, analyzing results, relating results to real world problems
and technologies.
• Encouragement through life
experiences
o Relate this activity to the experience of having
an x-ray. Emphasize how students are
discovering the concepts involved in
designing an X-ray machine.
• Motivation through having fun
o Introduce the activity as a fun learning
experience!
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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 [email protected]
o 303.492.6950
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