Groups are getting further and further in their bridge designs, ready to test how cars can cross over them, if the barge can fit under it, and the number of total weights it can hold before collapsing.  Some of our designs are so elaborate, that we now have to consider both the time it takes to design them and the number of materials we used.  These are REAL challenges that civil engineers face!

Every time second graders have class, they're one step closer to completing their bridge designs!  Some groups have completely finished their first bridge designs and have been able to test them for stability and strength.  

Be on the lookout as the bridge designs improve based on the data students collect from each of their tests!

With their plans approved by the head civil engineer (Mrs. Brinza!), second graders are off and running on creating their bridges from limited materials.

Working in teams, students are creating their bridges.  Once their bridge design is complete, they will complete a series of tests to determine if the bridges they designed can have toy cars pass over the surface, allow a barge to pass underneath it (see the picture to the left), and hold as many weights as possible.  Be on the lookout for the results of their tests! 

Second graders spent part of a class period brainstorming their bridge designs.  Now, working in teams, second graders are using their discussion techniques to design a bridge together.

Their plans must include a labeled diagram of their bridge design, including the materials they'll use!  

Next week, they'll begin testing their bridges to make sure they can hold weights, allow cars to pass over them, allow a barge to pass under it, and be wide enough to cross the span of a river. 

After they completed their bridge tests, second graders will be completing their culminating project in their civil engineering unit--designing and testing their own bridges!  Because engineers spend time brainstorming and planning out their designs, second graders will be doing just that!  Here are the details regarding their bridges!

Criteria--The Bridge MUST...
1.  Be at least 15 inches wide!
2.  Hold as many weights as possible.
3.  Allow a toy barge to sail under it.
4.  Allow toy cars to travel on top of it.

Constraints--What are you limited to?
1.  Materials!!!  

Second graders completed fair tests to see how many weights a beam bridge, an arch bridge, and a deep beam bridge could hold.  

A fair test would:
1.  Use the same weights.
2.  Have weights gently placed on the bridge.
3.  Put the weights over the span of the bridge, not the abutments.

Based on the results, they had to decide which bridge was the strongest and which was the weakest!  Check out some of their work!

Second graders have spent the last couple weeks becoming force experts.  They have learned that forces work in pairs and that if they are unbalanced, a structure can move.  For example, if we add too much weight to a structure, the structure will start to cave in.  It will need additional support from below to make the forces balanced.  Or, if the wind is too strong coming from the right side of a structure, we'll need to pull the structure towards the left to prevent it from falling over.

With safety their number one priority, second graders are now beginning to test three bridge designs:  beam bridges, arch bridges, and deep-beam bridges.  Learning the criteria for a fair test, they are seeing how data can support decisions that civil engineers must make.  Using everyday materials to set up models for these bridges, they are adding weights until each of the bridges fails.  

As second graders learn more about forces in science (balanced vs. unbalanced), we're putting that into action in engineering.  Using Legos, second graders had to work in teams to build a bridge but that met certain criteria.  A boat had to pass under the bridge and it had to hold the weight of a brick.  

Not all groups were successful, but their designs are giving them a better understanding of what balanced and unbalanced forces mean!  Way to go second grade!

Civil engineers must think about how different forces will interact with the structures they build.  Forces are defined as pushes or pulls, and they can come from many directions and with varying strengths.  

Will a force from the left cause a structure to sway to the right?  Will a force from above cause a structure to collapse below?  Second graders are identifying the strength and direction of forces.  And then, as civil engineers, they are posing solutions to these problems.  We want to keep the people who use these structures safe!

Second graders have finished their civil engineering story, learning ways in which the main character, Javier, has solved a bridge-building problem.  Learning about bridge parts and forces, Javier built many types of bridges, tested them out, and discovered the best solution to being able to get to his fort across the river once again!