Time
bullet45-minute free exploration session if students are unfamiliar with these materials
bulletAt least 1 hour for challenge activity

Preparation
bulletSeparate the materials into packets for each individual or group.

Groupings
bulletIndividuals or pairs

Materials
(per pair)
bullet50 plastic straws
bullet50 straight pins or paper clips
bullet1 or 2 feet of Strong tape (e.g., duct tape)
bulletScissors, for cutting straws
bullet10 weights (e.g., large washers or film canisters filled with sand)
bulletYardstick or meterstick (can be shared by groups)

Teacher Tips
bulletUse pins only if you think it's safe. Talk about pin safety and rules for working with pins. Rules might include no traveling with the pins, or that the pins must stay on the tables or in the straws. Warn students about pricking their fingers.

bulletHave students take the paper off straws the day before they'll then be curious about the upcoming activity.


 

 

Straws and Pins--Building out

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Context

Building out with straws and pins provides students the opportunity to experience many of the basic physics and engineering concepts inherent in structures. Building out means that most of the structure's weight is out and away from the point of support. Bridges (with support at two ends) and cantilevers (with support at only one end) are two straightforward examples of these types of structures. Building out emphasizes experience with the concepts of torque (the combination of force and distance from a pivot point) and center-of-mass (the balance point).

This activity provides a good opportunity to ask students to talk about bridges and cantilevers that they know. There are many bridges around to talk about. They range from monuments like the Golden Gate or Brooklyn bridges to simple logs thrown across a creek. Examples of cantilevers include balconies, awnings hanging in front of buildings, branches on trees, or even our arms when we hold them out. Discussion of examples like these invite your students to bring their own experience into the understanding of building out.


What Is It

If these are new materials, it is important to give your students time to freely explore with the straws and pins. Ask your students, "What can you build with 50 straws and 50 pins?" and let the students explore their ideas. Some teachers prefer to use straws and paper clips to avoid problems of getting stuck by pins, especially with younger students. However, building out (particularly cantilevers) is a good deal more difficult with paper clips. As their structures begin to take shape, suggest that they use bent paper clips as hangers for weights to test the physical strength of the structures.

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