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Linking Lessons

Children Go From Story That Features a Bridge to Building One Themselves

March 04, 1998

Not long after a new bridge was built across the gully that bisects the campus of UCLA's acclaimed University Elementary School, youngsters in a combined kindergarten-first grade class were reading a fairy tale in which a bridge played a central role. So what if the campus bridge did not have a troll under it, as the one in the book did--it was an opportunity to link a classroom lesson with the "real world" right outside the door. Lisa Rosenthal, one of the students' teachers, recounted the process of "building bridges," both in a literal and an educational sense.

Three Billy Goats Gruff

The children of Room 11 (5- and 6-year-olds) became interested in bridges after another teacher, Annette Marks, read them a story of the "Three Billy Goats Gruff." Because many bridges surround them at school, they had some prior knowledge of how a bridge is constructed and what its functions are.

A Conversation About Bridges


Teacher: Why was the bridge so important for the three billy goats?

Corey: Because they needed to go across it.

Gabrielle: Because there was lots for them to eat on the other side.

Teacher: What was the bridge's function? Why was it there?

Keith: Because there was a mean troll underneath.

Dana: And water.

Teacher: So the bridge was like a pathway to get to the other side, where the food was. What are some other things underneath bridges?

Hailey: Lots of mud and plants.

Julia: Places you can't walk.

Vivian: Trolls.

Teacher: What are some of the things that need to cross over bridges?

Leo: People and animals.

Anton: Big trucks.

Leo: Cars go over too, and they have to be really strong bridges.

Teacher: Which of the bridges at [the school] do you think is the strongest?

Dana: The north bridge.

Teacher: Why?

Dana: Because it's the longest.

Leo: Because more people go over it.

The Investigation


The next day, clipboards in hand, the children worked in groups to investigate the four bridges at the school. Their mission was to sketch them and note their distinctions, such as: How long they are, of what materials they are made, what is surrounding them, what supports them and which one might support the most weight.

The children then discussed their sketches of the bridges. And after examining the similarities and differences, someone suggested building a bridge. There was an enthusiastic response.

Before the building could begin, many questions needed to be asked: What will the bridge be used for? How much weight will it need to support? What materials will have to be used? How should the materials be arranged to make the bridge strong?

The teachers talked about the importance and usefulness of scale models to test designs and then gave students various materials to try. Children first attempted to build with clay. They molded and sculpted and were able to create a variety of designs. As soon as they finished their masterpieces, however, gravity began to take its toll. The clay bridges started to collapse!

Looking for the source of the problem, Dana took a ruler and measured the taller pillar of her bridge and then the smaller one. She figured out that she had to add one inch of clay to the smaller pillar to make it even. She also learned that her pillars might hold more weight if they were stronger at the base than at the top.

Then the children used wood. With hammer, nails and sandpaper, each budding carpenter came up with a unique bridge design.

After discussing which materials could be presented next, the teachers decided to let the children choose. Breaking up into small groups, the youngsters decided which materials from the classroom would be suitable for bridge building. From blocks to checkers, each group came up with a different medium.

Next, Brian Hurd, an industrial arts teacher and the father of Ian, one of the students, came to speak to the class about shapes used in construction, such as triangles and arches. He spoke about railroad trestle bridges, which use a series of triangles to give them strength. Brian pointed out that the school's north bridge is built with a similar design. The students decided they wanted to make a model of a railroad trestle bridge.

On his next visit, Hurd discussed the need for a plan or blueprint. Before drawing a plan, the children talked about their design and materials. Their model, they decided, would be constructed of Popsicle sticks and glue.

After building one railroad bridge, the children decided to build several more. Each student built individual spans, arranging the Popsicle sticks along the plan or pattern in triangles, and gluing the joints. After they were dry, the spans were connected to form trestles.

Next, Hurd discussed the importance of testing in construction--that structures must be inspected and/or tested to make sure they are safe.

After the bridges were complete, each was weighed. Julia recorded the numbers--the bridges ranged from 6 to 8 ounces.

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