Transcript SHPE Foundation Noche de Ciencias Hands

SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-on Activity Training
TeachEngineering Hands-on
Activity:
*Creepy Silly Putty
http://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub
_surg/cub_surg_lesson04_activity1.xml
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!!
http://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_surg/cub_surg_lesson04_activity1.xml
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Full Activity on TeachEngineering
• Material behavior and properties
• Engineering focus:
o Engineering Research/Analysis
• Students learn about viscoelastic material behavior, such as strain
rate dependence and creep, by using silly putty, an easy-to-make
polymer material.
• By seeing the viscoelastic behavior of silly putty, students start to
gain an understanding of how biological materials function.
• Learning objectives:
o Demonstrate two viscoelastic material behaviors (strain rate
dependence and creep) with silly putty.
o Explain the effects of borax concentration on the material properties of
silly putty.
o Explain sources of error in experimental data.
o Graph collected data using Microsoft Excel. (optional)
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
• Suggested time: 60 minutes
• Suggested group size: 3 students/group
• Materials
o
o
Each group needs:
• 2 plastic containers, for mixing water and glue, and water and borax powder
(such as GladWare tall square or deep dish plastic containers, ~ 6 x 11 x 5-in
and 6 x 9 x 7-in [L x W x H]; no lids needed)
• 3 disposable spoons
• 3 plastic bags that seal (such as Ziploc sandwich bags)
• 2 ounce (1/4 cup) measuring cup for fluids ($1 at Dollar stores)
• ruler
• stopwatch
• white school glue, 6 ounces
• marker, to label plastic bags
• soap and water, for cleaning containers and hands
• (optional) Creepy Silly Putty Data Analysis Worksheet, one per student
To share with the class:
• borax, 76-ounce box (aka sodium borate; available at grocery stores)
• 1 set of measuring spoons for solids ($1 at Dollar stores)
• (optional) computer and projector to show the Making Silly Putty Instructions
and Creepy Silly Putty Experiment Instructions PowerPoint files
http://www.teachengineeri
ng.org/view_activity.php?u
rl=collection/cub_/activities/
cub_surg/cub_surg_lesson0
4_activity1.xml
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Engineering Connection (Real World Application):
• Bioengineering/Biomedical engineering
• Bioengineers are engineers who study biological materials
and how they function in healthy and diseased states.
• Since biological materials exhibit viscoelastic behavior,
engineers must understand this behavior in order to fully
characterize these materials.
• Engineers may also design devices that come into contact
with biological materials.
• So, to ensure effective and successful device performance,
engineers must understand how the biological environment
reacts to the forces that a device imposes.
• Polymers such as silly putty also exhibit viscoelastic behavior
and can be used to demonstrate and learn about the
functioning of biological materials.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Engineering Connection (cont.):
• Silly putty can also be used to learn about and analyze
creep (deformation), which is a concern in other areas of
engineering, including civil engineering, structural
engineering, and mechanical engineering
• Engineers who design and construct technologies such as
nuclear power plants and jet engines must consider the
effects of creep.
https://www.llnl.gov/news/aroundthelab/2011/Feb/ATL021511_nuclear.html
http://www.grc.nasa.gov/WWW/k-12/UEET/StudentSite/engines.html
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Vocabulary Terms
Definitions/Equations
elasticity
When a material instantaneously returns to its original shape after a
force is removed.
viscosity
A measure of a fluid’s resistance to deformation. (For example, honey is
more viscous than water.)
viscoelasticity
When a material exhibits both viscous and elastic characteristics when
undergoing deformation.
creep (deformation)
When a solid material moves slowly or deforms due to heat or a force.
strain rate
Rate of change in strain (deformation) of a material. (How fast the
material creeps/deforms.)
polymer
A large molecule made up of repeating subunits. Biomaterials, such as
DNA and proteins, as well as synthetic materials, including many
plastics (styrofoam) are examples of polymers. Polymers exhibit
viscoelasticity.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Activity Procedure:
Part 1 – Making and Playing with Silly Putty
1. Have each group collect two containers, three spoons and three plastic bags.
2. In one container, mix 1 ounce warm water with ¼ teaspoon borax.
3. In the other container, mix together 2 ounces glue and 2 ounces warm water
until you have a uniform consistency and color. (It is important that this solution
be uniform, with no areas of excess water, or it prolongs the mixing time in step
5.)
4. While stirring, slowly pour the borax mixture into the glue mixture. Be sure that all
of the borax is transferred into the glue solution.
5. When the solution starts to thicken, mix with your hands instead of the spoon.
Continue to mix until a uniform solution is achieved and NO water is present.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Activity Procedure (cont.):
6. Store in a plastic bag labeled: “low concentration”.
7. Thoroughly clean both containers and discard the spoon.
8. Repeat steps 2–7 two more times, with 1 teaspoon borax (“medium
concentration”) and 2 teaspoons borax (“high concentration”),
respectively.
9. Make sure all bags are labeled with the concentration level and your team
name.
10. Play: Encourage students to explore the unique properties of silly putty
(viscoelastic behavior) and note the comparative differences in responses
to force by each batch. (For example: Stretch the silly putty at different
rates, roll the silly putty into balls and let it sit on a table, and form each
batch into a cylinder shape and hold one end of it, etc. Tip: While
exploring the silly putty properties, be careful not to mix up the different
batches or lose track of the borax concentration of each batch since
teams will need to know this for Part 2 of the activity.)
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Activity Procedure (cont.):
11. Have students share and discuss their observations as they pertain to materials behavior.
Does silly putty behave like an elastic solid or a viscous fluid?
Expected observations:
o
If you slowly stretch the silly putty, it is very pliable and seems to stretch forever; it
behaves like a viscous fluid.
o
If you quickly stretch the silly putty, then it breaks immediately, seems stiff, and behaves
like a solid with little elasticity.
o
The same material has two very different responses to a force depending on how fast
the force was applied.
o
Over time, the balls of silly putty on the tabletop deform and spread out, like a viscous
fluid.
o
However, you can hold the silly putty without a container and use your hands to deform
it into different shapes, like a solid.
o
While holding a cylinder of silly putty by one end, the silly putty slowly stretches and
elongates from its own weight.
o
So, silly putty behaves like an elastic solid and a viscous fluid depending on the forces
that are applied to it. Exhibiting both characteristics is the definition of a viscoelastic
material.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Activity Procedure:
Part 2 – Silly Putting Experimentation and Testing
1.
Have each group collect the bags of silly putty that students made in Part 1 (all 3
borax concentrations), a ruler and a stopwatch. Assign students the following specific
group roles to perform during the experiment and data gathering:
•
•
•
•
1 person forms and holds the silly putty at the same height
1 person holds the ruler and checks initial placement of the silly putty
1 person operates the stopwatch
1 person records data (if groups of three, assign this fourth role to everyone)
2.
Form the silly putty into a cylinder with a diameter of approximately 1.5 inches. (It is
very important that the diameter and shape of the silly putty be consistent for each
trial.)
3.
Hold the ruler vertically so that the "0 inches" mark touches the table.
4.
Hold the top end of the silly putty cylinder so that the bottom of the silly putty cylinder
is positioned 6 inches above the table.
5.
Immediately start the stopwatch. Keep the hand holding the silly putty stationary and
at the same height until the silly putty touches the table.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Activity Procedure (cont.):
6. Record the amount of time it takes for the silly putty to touch the table.
7. Repeat steps 2–6 with the same silly putty batch two more times, recording
the times.
8. Complete steps 2–7 for each silly putty concentration. (Expect students to
notice that as the concentration of borax increases, the amount of time for
the silly putty to creep 6 inches also increases. If students obtain
questionable results, run more trials and throw out bad data.)
9. Have students reflect on the data they collected by asking them the
questions in the Assessment section (next slide). Discuss as a class or assign
students to write down their own answers
10. (optional) Conclude by handing out the worksheets for students to
complete and hand in.
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Assessments:
Before the Activity:
o Questions & Predictions: Today you will make silly putty by mixing
together glue, water and borax.
• What do you think the borax does to the glue to form silly
putty? Record your hypothesis.
• Your group will make three batches, each with different
concentrations of borax (high, medium and low
concentrations). Write your predictions of how you think the
different borax concentrations will affect the silly putty: How will
the material properties change? Which concentration do you
think will be easiest to make?
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Assessments (cont.):
After Part 1:
o Revisit Predictions: Have students revisit their earlier predictions.
Discuss as a class or assign students to write down their own
answers. Ask the students:
• Was your hypothesis correct about how the borax
concentrations changed the material properties of the silly
putty? Explain. (As the concentration of borax increases, the
amount of time for the silly putty to creep 6 inches also
increases.)
• Did you see any differences while making the three
concentrations?
• Is silly putty an elastic solid or a viscous fluid. Which one? Why?
(Silly putty is both!)
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Assessments (cont.):
After Part 2:
o Data Reflection: Have students reflect on the data they collected and answer
the following questions.
• Did you have any variations in the time it took for the silly putty to creep
6 inches when you repeated the experiment for the same
concentration? (Expect students to say yes.)
• If so, what factors could have caused this? (Possible answers: Human
variability and error, for example, if the silly putty is not formed into a uniform
cross section cylinder, held in the same way for every trial, and held at the
same height while it is deforming.)
• Why do you think the concentration of borax altered the viscoelastic
properties of silly putty? (At this time, just have students predict why they
think borax is altering the properties of the silly putty. The answer will be
revealed to the students and discussed in more detail during the lesson.
Answer: Glue is a polymer, so on a molecular level it consists of strings of
compounds, similar to a plate of spaghetti. Borax reacts with the glue and
binds the strings together [cross-linking], similar to when a plate of spaghetti
starts to dry and all the noodles stick to each other. The more borax you add
to the glue, the more cross-links that form, resulting in a stiffer material.)
SHPE Foundation
SHPE Jr. Chapter Curriculum
Hands-On Activity Training
Creepy Silly Putty
Teaching tips:
o Emphasize the science concepts, vocabulary, and engineering
connection; reinforce these throughout the activity.
o Part 2 works best when specific team jobs are assigned to
students at the beginning of the activity and not varied
throughout the activity.
o Part 2 of this activity is very sensitive to human variability and error.
The force driving the creep behavior is the weight of the silly
putty. If the silly putty is not formed into a uniform cross section
cylinder and held in the same way for every trial, the results will
have a lot of variability and error. If students obtain questionable
results, run more trials and throw out bad data.
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 Research and Analysis: creating silly putty by following a
formula, taking quantitative measurements, analyzing results, relating
results to real world problems and technologies.
• Encouragement through handson learning
o This activity is very hands-on, and couples
“playing” with data collection and analysis.
• 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
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