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What is a bridge? It is a way or a path over to cross a river,railroad, canal,ravine, road, or other obstacle. 

Have you ever crossed, walked,droved a car, ridden a bike over a bridge?  Who cross the bridge? People, cars, bicycles, trucks, many heavy vehicles. 

What should a bridge be?  The weight of numerous people and vehicles must be supported by bridges without them collapsing. It must be strong and sturdy.

What makes a strong bridge? Choosing the appropriate materials is an essential component of bridge design. Another is ensuring sure the materials such as cement, wood, iron, etc. that make up the object are fashioned in a way that makes them as sturdy as possible.

Today we will have a challenge:

See how long the paper bridge can withstand the weight of the pebbles before it breaks.
Decide which piece of paper will be able to support the weight of the pebbles without collapsing first, and then perform your investigation.

Show three kinds of paper, a piece of paper, a paper folded into two and a paper folded into an accordion type or in an alternate zigzag fold. The students will see which of the three papers will hold the most number of pebbles.

Which of these three papers will hold the most number of pebbles? 


blocks/pile of books






1. Create two stacks of blocks or two books in each side.  Put them about two feet away from one another. 

2. Place a piece of paper in the center of each side, this will be the first bridge and before placing  a pebble on top ask the children to make a prediction and answer their observation sheet. Is it able to support its own weight?  Ask the children to  draw the result.

3.  Ask the kids to fold the second piece of paper into two so they may make the second bridge. Place the folded paper into the two stacks of blocks or pile of books, How many pebbles could their bridge support when the pebble was placed on top?  Is it able to support its own weight?   Ask the children to draw the result.

Variation: Ask the children to roll the piece of paper into a long tube. Place it into the blocks. Put the pebbles up. What do you noticed? 

4. For the third bridge, Take the paper and fold it into W shape. You will see these shape when you looked into the end of the paper in lengthwise position.  To do this, fold each half once lengthwise,alternately in accordion shape too. then once in the other direction. (for a total of three fold lines, dividing the paper into four equal sections). Like before, Place the paper in your blocks or pile of books. Put the pebbles on top. Is it able to support its own weight ?  Does it stay or collapsed? Ask the children to draw the result. 



My guess (Circle your answer)

  What I found out: (Draw)













What bridge stayed up best? Collapsed fastest?__________

How many pebbles did your bridge hold? ___________




Questions for Discussion: 

1. What happened to bridge number 1 and 2? The first and second bridge were not able to hold the pebble.The flat sheets of paper bent  quickly and sagged under their own weight same with two folded piece of paper. However in the next variation, the rolled paper long tube or a cylindrical shape, it was able to hold a bit, because it increases it stiffness.

2. What happened to the third bridge? It was able to hold a lot of pebbles. Why does this happen? Though the material is the same but the shape affects how easily it bends. If you fold it into a W shape or an alternate accordion shaped, It formed a triangle shape. The bending stiffness is important in a bridge. Though it it is made of cement, wood iron etc. the most important thing that civil engineers looked for and consider is the shape and design of the bridge. 

3. What is in the triangle that makes it the strongest shape for the bridge?

When you look at a bridge made of steel or wood, you will frequently notice triangle forms making up the majority of the bridge's support system. These are referred to as truss bridges. Since they allow weight to be distributed evenly throughout a structure, triangles are the most structurally strong shape and can handle heavy loads.

A triangle is the strongest straight-edge shape since it cannot be collapsed without breaking one of its sides. Triangles are common in bridges because of this. Bridges with triangle designs are meant to carry cars and the bridge's weight downward without bending.



4. Can you give other examples of things that make the shape of it to support  something.? For the rolled up shape long tube or cylindrical shape,  we can see this at  classroom desks and chairs with metal legs. Are the legs made of tubes or flat metal pieces? Why do you think cylinder-shaped tubes could be more effective at bearing a person's weight than flat objects are?


 The triangle shape and their formations, including roofs, radio towers, crane arms, swings, and many more, also use truss layouts or triangle shape.










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