Lyvonia Hearns - Asa Philip Randolph 

Building A Straw Power Tower 

Lyvonia Hearns Asa Philip Randolph
7316 S. Hoyne
(773) 535-9015


To explore the effects of shape, materials, and balance in building a Straw
Power Tower that can support the most pennies. Towers must be at least 58cm
(23in.) tall. This activity is for students in grades 2-8. Divide the class
into teams of 5 or less.

Materials Needed:

Per Team
Lab Report Contest Rules 50 Glad straight straws
hole punch many pennies 120 small metal paper clips
2 large paper clips scissors 5 clean, empty 1-pint milk or juice cartons
measuring stick table, desk, or floor


Set aside 15 straws from the 50 you were given. With your team begin to build
a Tower from your straws and paper clips. It can be any shape you want, but you
can't use any other materials. Stop building when your 15 straw tower stands up
by itself. Make a Weight Basket out of the 1-pint milk carton. Use the large
paper clips to attach the weight basket to the tower. The Basket must not touch
the ground or floor. Slowly add 20 pennies to your Weight Basket. Where does
your tower sag or bend? If you need to, add more pennies or jiggle the basket.
Could these weak spots collapse under more weight? Remove your Weight Basket.

List Your Variables Pick one weak spot on your Tower. What change could make the weak spot sturdier? Anything you could change on your Tower is a variable. Now with your team make a list of changes that might improve your Tower in general. Some variables to think about are: Shape- Could you make a square or polygon (many sided shape) into triangles to
make it stronger?

Strength- of beams- Could you combine 2 or more straws to make a beam

Length of straws- Could some beams be longer? Should some be shorter (cut

Joints- Are there other ways to connect the straws?

Locations of strong beams- Should the strongest beams be near the top of the
tower or the bottom?

Size of foundation (base)- What effect does changing the size of the foundation
have on your Tower?

Location of Weight Basket- Does it matter where you attach the Weight Basket?
(The bottom must be at least 20cm (8in) off the ground.)

MAKE A CHANGE Choose one variable from your list. Make the change to a weak spot on your Tower. Make one change at a time. (For ex., if you change to longer beams, don't also change the size of the foundation.) Why is it important to change only one variable at a time? Record the variable you changed on your lab report next to "15-Straw Tower" Now test your change. Attach the Weight Basket to the exact same spot as before. Add 20 pennies and observe your Tower. Did the change make the weak spot sturdier? Record the results. Keep Building Set aside 15 more straws from your 50. Continue to build and strengthen your Tower. After these 15 straws have been added, test your Tower with a Strength Test as before. Then change one variable that could make the weak spot stronger. Add the last 20 straws to your Tower. Repeat the Strength Test. Make the final changes until your team is satisfied with your Tower's strength, shape, weight Basket attachment, and height. Performance Assessment:

Name your Tower. Measure, record, and sign off its official height on your lab
report. Gently add pennies to the Weight Basket, counting one by one. How many
can the Tower support before the Weight Basket hits the table? Enter your penny
count on your lab report. Now write a paragraph on the back of your lab report.
List the features that made your Power Tower strong, explaining how each helped
the Tower's weak points. Describe your Tower's weak points. What made it
finally collapse?


Display your Straw Power Towers around your classroom. ENJOY!


Super Science Nov./Dec. 1998

Return to Physics Index