Bridge Building for a Rainy Day

This is the recent activity I hosted with some preschoolers and school-age children at Catalina Day School. After several recent rainy afternoons during our own summer vacation in Ohio, I had some time to  write down the specifics so I can share it with you. This activity, in itself, is a great rainy-day activity.

Materials:

Red cardboard bricks (the preschool variety; alternatively you can use a pile of books on either side of the bridge)
Dixie cups (1 per child)
Pennies (50 per child)
Construction paper (5 half-sheet strips per child, cut along the length of the paper)
Photos of different types of bridges (arch, suspension, beam, truss, etc.)
5- or 7-inch Lincoln Log block (1 per child, used to keep bricks at standard distance apart)

Introduction:

I like to pose some questions at the beginning:

Have you ever seen a bridge?
What are bridges used for?
Do we have any bridges in Tucson (or wherever you live)?

Bookmark or print some pictures from the Internet of different types of bridges (Arch, Suspension, Beam, Truss, etc.). Feel free to go into as much detail as you feel is appropriate on bridge types, depending on the ages of students doing the activity. A good introductory website for understanding bridge design is:

http://www.pbs.org/wgbh/buildingbig/bridge/basics.html

Activity:

A. Fold the construction paper (for preschool-age and Kindergarten students, fold these sheets ahead of time).

1. Leave 2 half-sheets unfolded.
2. Fold 1 sheet accordian style, along length of paper.
3. Fold the last 2 sheets so that the edge (along the length of each side) is folded up approximately 1 inch on each side (they will look a little like hot-wheel tracks).

B. Arrange the sides of the bridge and the “river."

1. Place the Lincoln Log between the two cardboard bricks so that it is perpendicular to the bricks. 
2. The 5- to 7-inch space between bricks now represents where the “river” runs under the bridge.

C. Start testing the bridge designs.

1. Have students lay one flat half-sheet of paper to span the space between the bricks.
2. One by one, place pennies in the middle of the bridge. The pennies can represent people or cars. How many people can the bridge support before it collapses?
3. Remove the pennies and try placing another flat piece directly on top of the first one, so there is a double layer of construction paper spanning the bridge.
4. How many pennies can the bridge hold this time?
5. Remove the 2 flat pieces and place 1 of the "hot-wheel-track” pieces (with the folded sides oriented upward) across the river. Place pennies on the bridge, one by one, in the center of the bridge. How many can it hold now?
6. Remove the pennies and place the other “hot-wheel-track” piece (folded sides oriented downward) on top of the other piece. This will leave a pocket of “blank space” between the two, along the length of the sandwiched pieces.
7. How many pennies can it hold now?
8. Remove pennies and bridge. Place the accordion-style bridge across the gap. Add pennies to the center until it collapses.
9. Which bridge type was most successful?
10. Now try using a combination of your bridge types to create a maximum-strength bridge that holds a record number of pennies!