Problem solvers to the rescue

Problem Solvers to the Rescue
A town needs water, and there’s only one rickety bridge—can these student scientists calculate a safe amount of water to transport?
By Frances V. Figarella-García, Lizzette M.Velázquez-Rivera, and Teresita Santiago-Rivera

PHOTOGRAPHS COURTESY OF THE AUTHORS

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ach group of super scientists prepared for the next challenge: running the truck model over thebridge. The students were anxious to test their predictions. This was the final test for the groups, where they tested their calculations and attempted to transport 840 g and 780 mL of water over a bridge without the b ridge breaking. Would they make it? Were their calculations accurate?

Imagine … you are responsible for bringing water to a hurricane-ravaged area. There is only one bridge andonly one truck, and the bridge can only hold so much weight. Your calculations determine if the truck—and its load of water—can make it safely over the bridge. This is a typical challenge during two-week summer camps for third- through fourth-grade students held in the Construct, Discover, and Learn (CDL) schools across Puerto Rico. The camps—and the CDL schools in which they take place—are part of asystemic professional development program sponsored by the Puerto Rico Department of Education to support the development of inquiry-based science and mathematics instruction for elementary students.
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Figure 1.

A KWH table.
A Know-What-How table helps students synthesize the information at hand before solving a problem.

K
• The bridge is frail. • The community has almostno water. • The town’s mayor has a truck available to transport the water in one trip.

W

H

• What is the maximum mass of the truck? • How is mass measured? • What is the maximum volume of water • How is volume measured? that could be transported?

Our school, University of Puerto Rico Laboratory School in San Juan, is a designated CDL center in which summer camps are held. Through theassistance of university faculty, our center has provided more than 120 teachers guidance and support in implementing inquiry-based instruction. This article describes a typical camp session and some of the things we (a university professor and two classroom teachers) have learned from our experience as camp coordinators.

7) Present the solution to share and demonstrate the knowledgeconstructed.

Water Over the Bridge
To present the problem to students, we held a hypothetical public hearing in which two teachers, representing the mayor and a community member of a town in Puerto Rico, dramatized the following scenario: The community member was seeking help from the mayor because the town was running out of water. A hurricane had damaged a bridge in town that was the only way to getinto the community. A provisional yet fragile bridge substituted the original one, but vehicle transportation was restricted. The mayor was willing to provide a municipal truck to carry the water, but he didn’t know if the

A Problem to Solve

Since our program began in 1999, we have focused on the design of science curriculum units using the constructivist methodology of Problem-Based Learning(PBL). We decided to plan lessons specifically related to the concepts of mass and volume because 1) these concepts are not commonly taught at the elementary level in Puerto Rican schools, even though they are fundamental concepts for this level; and Students practiced using a platform balance and weighed various objects. 2) even when these concepts are taught, it is often done in a traditionalway—through the use of the textbook, without hands-on activities (Gabel 1994). Delisle (1997) introduced a specific structure that facilitates the use of PBL, which we adapted to suit our instructional objectives. We followed these steps: 1) Present the problem, 2) Generate possible solutions, 3) Explore what is known using a KnowWhat-How (KWH) table (Fosnot 1996; Brooks and Brooks 1993), 4)...