Keeping You In Suspension

By: Sarah Conner

#My Idea

This project is testing which materials are best for building bridges.


straws, duct tape, Scissors, 2 large paperclips, 2 small paperclips, paper cup (at least 8 ounces), 300 pennies, metric ruler, notebook, pencils


Will straws or pencils hold more pennies?


I think that the pencils will hold up more pennies because they are stronger.

Independent Variable

Straws, Pencils

Dependent Variable

Amount of Pennies

Controlled Variables

Cup brand, type of paperclips


1- If your straws are the flexible type, cut the flexible type off.
2- Cut ten straws this way.
3- Make sure they are all the same length.
4- Cut 2 pieces of straw, each 3 cm long.
5- Tape 2 long straws on both sides on one of the short straws.
6- Do this at one end of the long straws.
7- Then tape the long straws together at the end.
#8- This is a tower for your suspension bridge.
#9- Redo step 5-8 to make a second tower.
#10- Tape one tower to a piece of furniture.
#11- Tape the second tower to a piece of furniture the same height.
12- Position the 2 towers far enough that you can place a straw in between.
#13- Place another straw between the 2 towers so its ends rest on the short straws.
14- This straw is the bridge deck.
15- Now you have a simple beam bridge.
#16- Make a load tester by unbending a large paper clip into a V shape.
#17- Poke the ends of a thick cup, just below the thick rim.
#18- Use a second large paperclip to hang the load tester over the bridge deck.
19- Do this by attaching the 2 large paperclips together, and then sliding the new one around the bridge deck straw.
#20- In your lab notebook, make a data table which has 3 trials and the number of pennies in each trial.
#21- Add pennies in the paper cup until the bridge fails.
#22- Record how many pennies it held on the first trial and then do it 2 more times.
#23- Now, to do the same things but with pencils, you take 5 unsharpened pencils and 2 thin glue sticks.
24- So take 1 glue sticks and tape 2 pencils on both sides of the glue stick.
25- Repeat that again to make a second tower.
26- Tape 1 tower on apiece of furniture, and tape the other tower on a piece of furniture that is the same height.
27- Take the last pencil and place it between the pencils so it can lay on the glue sticks.
28- Use the load tester from the previous part of this experiment, and hang it of the pencil in the middle.
29- Keep adding in pennies until it fails.
30- Record how many pennies that it held in your lab notebook.
Big image


It turned out that the pencils held more pennies than the straws.


My hypothesis was correct because the pencils did hold more pennies then the straws. The importance of this project.