Hello STEM Friends!
Are you ready for a little bit about bridges?
We have built a lot of bridges in STEM Class!
In fact, you can read more about bridges right here:
I knew students loved bridges and I was looking for a different kind of bridge when I happened upon an article about a gliding bridge. In Nepal, people in remote villages build a bridge that crosses rivers by installing a rope across the river. Dangling from the rope is a passenger carrier and once you are seated in the carrier the passengers pull on the rope to glide the carrier across the river. What they really need is a bridge like the one in the above photo but these are quite costly. Instead they often have rigged up their own version of a foot bridge or a gliding bridge- and in many cases these have been disastrous.
We watched videos about the bridges in STEM class and then decided to try to build a model.
First, we had to decide what a gliding bridge is!
After a little research we determined that a gliding bridge is a rope pulley system that carries passengers across a river or canyon by means of the passengers themselves. Once seated in the carrier the passengers reach to the overhead ropes and pull until they have crossed over to the other side. What makes this work is two things: great supports on each side of the river and pulleys or some kind of ability for the rope to be easily pulled.
Knowing that the supports on each side of the river were very important led to the first decision each team had to make. They were given a choice of what material to use for their anchors on each side. We used two lab tables that were about 2 feet apart for our river banks. The kids could choose from three types of foundations- rocky soil, sandy soil, or clay.
The next decision was the passenger carrier. What should it look like? Wow! We had so many different ways to cross that river! Our passengers were ping pong balls! Again, the kids had to choose from available materials and decide how to build the carrier. Some of them chose craft sticks! What do you think happened when these carriers were tested? (Hint: They might have been heavy!)
This challenge presented so many dilemmas! One of the biggest problems to solve had to do with connecting the "rope" for the pulley system. Kids learned very quickly that the rope had to be securely attached to the support on each side. Look at the clever ways they found to attach the rope! The photo on the bottom right is a pulley the team designed!
To test the final bridge system kids had to demonstrate a crossing. We all cheered if their passenger car made it across without a mishap! What a fabulous real life model we built and the learning was just amazing!
So, there you have it- that's what we have been doing in the lab! How about you?