Designing and Building Bridges Activity

Set up a fun science and engineering activity for kids using everyday materials to construct a bridge together! Make it into a challenge to see how much weight the bridge can carry and compare results using different methods and materials.

Today we are participating in a fun science series along with Inspiration Laboratories and Science Sparks called Challenge and Discover! We are setting a fun challenge for ALL of our readers to participate in along with us, whether you have your own blog or not, and hopefully you will share your ideas with us in our link up or directly on our Facebook walls.

Here os the exciting challenge as we set it to our own kids and now to you too:

Can you design and build a bridge using everyday and recycled materials that will bear a 1kg (approx 2lb) weight?

I gave the girls a huge pile of drinking straws, some sellotape, two building blocks to create a bridge support and a 1kg bag of sugar as a weight to test. Immedaitely Cakie laughed and said “those straws are WAY too bendy, they won’t work!” We put just one straw across our blocks as a fun test to see what would happen and quite obvious it couldn’t bear any weight at all!

Then she proposed laying many straws next to each other, loosely, over the blocks. I asked her to predict what she thought would happen and she said “the bag won’t stay up, it will fall I think.” And she was right, the straws just separated form each other and rolled away.

I pointed out the tape and asked what did she think we could use it for? She wanted to try taping them together to make a raft type shape, so we did that and it made the straws much more solid as they held together. They did indeed hold the bag of sugar when it was placed on top, but it bowed in the middle and wasn’t a strong bridge! Could we improve the design? What would make it even stronger?

We made a second straw raft shape and taped it together, then layer it over the top of the first at opposing angles. This was much stronger and didn’t bend at all under the weight. In fact, it could carry 2 or even 3 kg easily!

Our final attempt to try something different was to roll up the straws into bundles and tape them around the middle. By placing a few of these next to each other we formed an incredible strong structure that could take a lot of weight on top! We wondered if some engineers use cylindrical bundles in a similar way and also if we could find a similar structure in nature. We are going to do some research into those last two points and find out together.

Now it’s YOUR turn! Can you make a bridge from recycled materials that will bear a 1kg weight? Write it up and link to to our linky below (open until May 10th.) Don’t have a blog? Simply take a photo and upload it to our Facebook page instead! We would love to see your ideas!

Extensions activities for older children:

Draw their designs first, labelling which materials they would like to use and why

Compare two or more materials using the same design and see which one can take more weight

Try making the same design on a much larger scale, with two cardboard boxes as the base units

Can you make a bridge that can bear the weight of a child?

Photograph the steps taken and print them off to make a book, then write underneath all that they did

What they are learning as they play:

science: predicting and testing skills, cognitive development, strength of materials, construction, weight bearing, engineering

creativity: combining materials to create a 3D object, using recycled materials in creative ways

Cakie: 4.6

Pop: 3.0

Bean: 13 mos