Mechanical Engineering Lesson:
Testing Sail Designs
Students explore how different materials are
affected by wind as they determine the optimal
shape, size, and material to be used to create a sail
for moving a raft down a string track.
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To build the track tape two plastic straws to the bottom
of a foam raft. Run fishing line through each of the
straws and tape each end of the line to a table. Cut a
small slit in the raft (where sail mast will be inserted).
Students make “sails” by building a sail on a craft stick
mast. First, students use worksheet 1 to predict which
materials and shape they think will make the best sail.
Next, they build and test their sail design.
To test the sails, students insert the craft stick sail mast
into the foam raft, and a fan pushes them along the
tracks. Success is measured by the distance the raft is
able to travel along the track.
Encourage students to follow the steps of the
engineering design process (ask, imagine, plan, create,
improve) as they design their sail and to continue
improving and testing their sail design. When students
have finished, have them complete worksheet 2.
This activity is
intended to have
students design
efficient sails—ones
that can use even a
small amount of
wind to travel across
the track. Speed is
not the goal.
Objectives: Students will be able to
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predict which materials will make the best sails.
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observe and describe how well different materials and
shapes catch the wind as sails.
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notice that the material and shape of a sail affects how
well the wind can move it.
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compare the performance of sails and decide which
properties (for example the stiffness of the material or
the size of the sail) have the greatest effect on sail
performance.
Preparation: 15 minutes
Lesson: 40-50 minutes
Materials
For the Class
♦ photographs of modern and ancient
sailboats
♦ ruler
♦ fan
♦ 2 pieces of thin string, each 5-6 feet
long or 2 pieces of fishing line, each
8-10 feet long
♦ masking tape/duct tape
♦ 2 foam trays
♦ 4 plastic straws
♦ fan
♦ 4 craft sticks
For Each Group
♦ scissors, tape, glue
♦ craft sticks
♦ coffee stirrers
♦ index cards
♦ copy paper
♦ paper/foam cups
♦ tissue paper
♦ plastic bags
♦ fabric scraps
♦ aluminum foil
♦ wax paper
♦ napkins
Vocabulary
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mast
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material
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sail
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property
For more information on the
Engineering is Elementary
Curriculum visit www.mos.org/eie
Name: _____________________________________ Date: ________________
Be a Mechanical Engineer!
1. Circle the material you predict will work best to design a sail.
aluminum foil
paper
plastic wrap wax paper
other
Why? _____________________________________________
___________________________________________________
2. Circle the material you predict will NOT work best.
aluminum foil
paper
plastic wrap wax paper
other
Why not?___________________________________________
___________________________________________________
3. Circle the shape you predict will work best for a sail.
square
triangle
circle
other
Why? _____________________________________________
___________________________________________________
1
Name: _____________________________________ Date: ________________
Testing Sail Designs
Illustration by J. Martin
Pick your best sail design. Describe what happened.
1. How far did your sail go? Draw it.
end
2. How floppy was your sail? Circle the best choice.
very floppy
a little floppy
Draw a picture of your best sail design.
2
not at all