| This task is designed
for all junior students (grade 4-6) for the 2011-2012 school
year. We are now in our second three-year task cycle and
the focus of this task is: Forces
Acting on Structures and Mechanisms. The task is designed
so that students from grade 4 to 6 can enter into it in different
ways and to different extents and still achieve the overall
expectations. The goal is to bring teachers and students within
a division together in order to increase collabloration and
expertise in the area of technological design. Teachers /
divisions / schools will decide when the task is to be completed
within the school year. Invention Conventions, Structure Showcases,
etc are encouraged upon completion in order for students to
demonstrate their work.
Students from each school will be invited to showcase their
project designs in London District Catholic School Board's
annual Junior Tech Challenge. This evenit is held in conjunction
with the London Distict Sciene and Technolocy Fair, normally
scheduled for the first weekend in April. Information about
Tech Challenge will be communicated to schools and teachers.
If at any time, you have questions, etc about the project
please fell free to contact Sharon Gillies via email (sgillies@offfice.ldcsb.on.ca)
or phone (519-663-2088 ext. 42104).
It is hoped that the task will continue to grow and be improved.
This can only happen with your imput and feedback.
In 2012-2013, the junior division project will focus on Pulleys
and Gears. The 2010-2011 focus was on Electricity.
Lead-up to the Challenge Task....
Here are a series of activities that will help students learn
the basics about forces and structures/mechanisms so that
they can enter into the challenge of building a Rube Goldberg
Machine.
1. Introduce the topic of forces. By the end of the
discussion students should be able to define force as a push
or pull and undersand that the name of a force is based on
whatever causes the push or pull.
Some questions you might pose are:
1. What is a force?
2. Can you think of examples of forces that can move an object?
3. Can you think of examples of forces that can push an object?
4. Can you think of examples of forces that can pull an object?
5. Can you think of examples of forces that can change the
shape of an obejct?
Formal definitions for a number of foces are given below and
on the student page of this task but students do not need
to memorize these.
| force |
a push, pull, or other factor that can make an object
change speed, shape, or direction |
| applied force |
a force applied to an object by a person or another
object directly pushing or pulling on it |
| contact force |
a force that resutls when two interacting objects are
in contact (touching) with each other. examples: applied
force and friction |
| friction force |
a force that resists movement between two objects in
contact, friction usually causes an object to slow down,
example: rolling a ball on carpet |
| gravitational force |
the natural force of attraction from the earth that
causes objects to be pulled down |
| magnetic force |
a force produced by magentic materials that attracts
(pulls) or repels (pushes away) other magnetic materials |
| noon-contact force |
a force acting between two objects that are not touching,
example: gravitational and magnetic forces |
| tension force |
a force that acts that causes an object to expand, stretch,
or lengthen, a force that travels through a string, rope,
or wire when it's pulled tight |
| torsion force |
a force that causes an object to twist, also called
torque |
| spring force |
a force exerted by a compressed (squeezed) or stretched
string |
2. Forces in Our Environment:
(tornadoes, hurricanes, earthquakes, tsanamis)
Jigsaw Activity:
** this activity should be no more than one hour total. (home
group introduction - 5 minutes, expert group information gathering
- 30 minutes, home group sharing - 5 minutes for each phenomena,
20 minutes total)
Step 1: students work in home groups of four, one student
in each home group chooses or is assigned one of the natural
phenomena: tornadoes, hurricanes, earthquakes, tsanamis
Step 2: expert groups for each phenomena can form to gather
information possible questions for the expert groups are:
 |
Tornadoes:
1. What is a tornado?
2. Where does the force of a tornado come from?
3. What kind of damage can a tornado inflict on the structures
(homes, schools, etc) around us? |
 |
Hurricanes:
1. What is a huricane?
2. Where does the force of a hurricane come from?
3. What kind of damage can a hurricane inflict on the
structures (homes, schools, etc) around us? |
 |
Earthquakes:
1. What is an earthquake?
2. Where does the force of an earthquake come from?
3. What kind of damage can an earthquake inflict on the
structures (homes, schools, etc) around us? |
 |
Tsuanmi:
1. What is a tsunami?
2. Where does the force of a tsunami come from?
3. What kind of damage can a tsunami inflict on the structures
(homes, schools, etc) around us? |
Sample summary sheets for each student to complete
in their expert group are attached. Please feel free
to use them (or not) or change as you feel necessary to meet
your class' needs. (tornado, hurricane,
earthquake, tsunami)
Step 3: students regroup as home groups so that each student
can share the information on their phenomena
3. Measuring Force:
Using the Spring Scale to Measure Force
- demonstrate how to use a spring scale
- brief discussion of what a Newton is as a unti to measure
force
- groups of students work to make force measurements on a
number of objects
- keep one class data chart for a quick discussion on which
objects had most, least force and why
OR
Here is a site that gives a very similar
short activty. In this activity, a "forcemeter"
is a spring scale.
http://www.standards.dfes.gov.uk/schemes2/science/sci4e/sci4eq2?view=get
4. Focres Acting on A Strucure:
A structure can be defined as a stationary framework of interconnecting
materials that can endure forces such as gravity, wind, mass,
and pressure. Structures can be anything from footstools to
bridges to gigantic buildings.This activity is best done in
groups, your choice of size. Each group needs paper (you can
provide an unlimited supply or limit the amount, good way
to use recycled or scrap paper), making tape, some books (whatever
is around is fine) and the attached recording
sheet.
Activity Outline:
The challenge is for studetnts to make a structure out of
paper that will support the most books at a height of 21cm
above the tabletop. The structure must be free standing, students
may not use their hands to support it.
Paper can be shaped into cylindrical columns,
triangular prisms, rectangular prisms,
and other shapes that students discover.
Have each group of students carry out four trials in order
to come up with a final design that holds the most books.
After the first trial, students can change their structure
or build another based on what they observed when books were
placed on their first structure. They then test their second
structure and continue this process until they have done four
trials. Students complete their recording sheet as they work
through the trials. After four trials, each group should build
a copy of their structure that held the most books.
Groups demonstrate the strength of their best structure for
the class.
After the demonstrations, the concept of compression should
be clear to all students. The paper structure bearing the
weight of the books is compressed as the books press down
on it. What happens to a structure as a result of
a compression force?
5. Your class may be interested in checking out The
Force Lab to see how forces (squeezing, stretching, bending,
sliding, and twisting) affect structures.
To view this online, your computer needs Flash. It can be
downloaded for free from the link provided so students could
check out the site at home with their parents.
| About The Force Lab
This lab simplifies the real-life forces and actions
that affect structures, in order to illustrate key concepts.
Introduction:
Forces act on big structures in many ways. Click on
one of the actions at left to explore the forces at
work and to see real-life examples. |
6. How does a lever work?
Please see attached experiment
for students to complete.
7. How does a pulley work?
A pulley is a form of lever. The centre of the pulley acts
as a fulcrum. The load is attached to one end of the rope
and the working effot occurs at the other end of the rope.
A simple pulley can replace a long lever bar. To lift an object
you just pull down on the rope.
Demonstration Pulley: Prior to the lesson,
construct a model of a pulley system to use for demonstation
and discussion in class.
Here is a link to a Visual
Instruction Plan for building a pulley system.
OR
An instruction
sheet is attached to help you in this construction.
In your school's tech kit there are plastic spools and wooden
wheels with grooves. Either can be used as pulleys.
plastic spools:
|
wooden wheels with grooves:
(ignore mounting)
|
Add gram weights to the yogurt cup on the single and compoind
pulley and lift the cup by pulling on the loop at the loose
end of the sring.
What is the advantage of the pulley? Is there a difference
between the single and compound pulleys?
An alternative to the above is this online demonstrations
that you can either show students or they can chech out to
see how a pulley works:
http://www.walter-fendt.de/ph14e/pulleysystem.htm
8. Gears Systems:
Gears and Force
Plastic gears of three different sizes are included in your
school's tech kit for use in this activity.
9. Students are now ready to begin the Challenge Task:
Rube Goldberg Maching: "Tee It Up". A Student
Booklet is attached if you choose to use it to guide students
through their design and build work.
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