Loads Lab Educator Support
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After doing the Loads Lab, have kids do this hands-on activity to practice designing a bridge that can support its dead load plus a live load of pennies (and environmental loads in the Build on It extension).

Paper Bridge

Introduce the Activity
Hold up a single piece of paper. Ask: How many pennies do you think a bridge made out of this paper can hold? After kids make some guesses, lay the sheet of paper flat across two books placed 20 cm (about 8 in.) apart. With the kids keeping count, place pennies on the bridge, near the middle, until the bridge collapses (it will hold only a few). Now introduce the activity challenge.

Lead the Activity

• Ask questions about kids' designs: What can you do to the paper to make it stronger? Should you cut the paper? How can you use the paper clips? (Kids may accordion-pleat the paper, roll it, or cut it into strips and weave them together. The paper clips could be used to stiffen folded paper.)
• When kids test their bridges, suggest that they observe their bridges closely to determine where they fail.

The Big Idea
Changing the way materials are used can change their strength in a structure. Although a piece of paper seems flexible and weak, it can be folded, rolled, twisted, or otherwise altered to support quite a bit of weight. Shapes that incorporate triangles (such as pleating) or arches (such as rolling) help to carry the compression force created by the live load on top of the bridge. Follow up with the Shapes Lab or Forces Lab.