Bridge Building Series - Truss Bridge 1

Truss bridge building instructions 1

We’ll make different truss bridges using two different materials - foam cubes and cut drinking straw pieces.

Design Rules for both bridges:

1.      Bridge must span 10 inches (25 cm)

2.      Bridge must have a place to attach a small cup in the center of the span (preferred).

3.      The ends of the bridge are not taped onto the support structure.

Bridge 1 – Marshmallow/foam cubes/cheese balls & toothpicks

NOTE: The best material for this project is foam cubes. However, a container of foam cubes can get very expensive (I've paid $27.49 for a container of 105 foam cubes), so if you can find more affordable ones, please let me know.

I've done this project with marshmallows, and it's doable (for intermediate grades). And cheese balls get messy, but doable as well.

Supplies:

·         A bag of marshmallows, foam cubes, or cheese balls

·         A box of toothpicks

·         Tape

·         Small cups

·         Paper clips

·         Weights – pennies, paper clips, etc. Anything is OK as long as they weigh the same. You want to compare how much different bridge designs can support

    

Instructions:

1.   Create a square with four foam cube pieces and toothpicks. Create 3 more. Put them together to create a cube. 

2.   Create several more cubes and put them together until you reach 10 inches in length. Remember, your bridge must be longer than the span it needs to bridge (add an inch or two to the total length of your bridge).

  

3.   Place the bridge between two desks, tables, chairs, etc.

4.   Hang a small cup in the middle of the bridge (use hole puncher and paper clips) and load it with pennies, paper clips, etc. to weigh it down and test its strength.

~same number of coins in the cup as the beam bridge project

added another cup of coins

added more coins to each cup

Again, this project works best with these foam cubes. I purchased from Amazon, but they are pricey. I did find some smaller foam cubes from the Dollar Tree store, and they worked well. But it's very difficult to find them consistently. You can see them on their online store, and the store managers don't seem to know when or if they'll ever get another shipment. So, if you find another source of reasonably priced foam cubes, please let me know.

Fantastic Foam Bridges - March 30, 2015

I do a lot of hands-on building projects because the students seem to enjoy them the most. This project is a variation on a marshmallow bridge project. This one is really exciting for the students because there's an element of competition, which brings and urgency into the situation.

 Supplies List:

•     Foam cubes - it doesn't matter what the size is unless it's really small. 1 inch foam cubes work pretty well.
•     Toothpicks
•     Small cups to hold pennies (tiny cups you'd get from a dentist's office)
•     Paper clips
•     Pennies (up to 700 pennies)
•     Plastic tub (to catch the pennies if/when the bridge collapses)

I draw a couple of truss bridge designs on a white board and talk about the triangles in the bridge design. Then I go on to talk about the advantages of using triangle; however, I caution them about the hypotenuse. With the toothpicks, the students have to do something about the length difference.

Project Instructions:

1.     Hand out a tube of foam cubes and ~250 toothpicks to each team of students.
2.     Build whatever shape the team wants to build.
3.     Build, test, & build, again!

Here are some records to break for next year:
 
2nd graders - last year, 298 pennies
3rd graders - this year, 250 pennies
4th graders - this year, 450 pennies
5th graders - this year, 650 pennies

I don't have a lot of class pictures because I have to load the pennies very carefully, evening out the load on the bridge. So, the teachers take the pictures, but I haven't received the pictures, yet. So, here's what I have.

~150 pennies in the right and the left cups each

Try this one at home and have a wonderful time.

P.S. - The only problem with this project is that the foam cubes are quite expensive (between $17.95 - $24.95 per 102 cubes), and we can't keep reusing the foam cubes. So, it does get expensive for a class project when I try to collect $10/year/student for the science projects. If you know where I can get them cheaper, please let me know.