SWBAT design and build a structure that will support weight.

We can use triangles to make a gumdrop structure strong and stable.

**Activity Description**

Watch the cartoon to see the short activity description.

**NGSS/Common Core Connections**

In this lesson, the children will be building a physical model to illustrate how the shape of an object, such as triangles, helps it function. It will also help build knowledge about how the shape of a designed item will influence its structure and function. At the end, the children will test their gumdrop structures and the class will collectively draw conclusions about how the shapes used in the structure add to its stability and/or strength. This knowledge will give them a solid foundation for when they build their own tower at the end of the unit.

**Materials**

(click for a photo of the materials)

- gumdrops-- 12 per group
- toothpicks--at least 20 per group
- *Note: I put the toothpicks and gumdrops in a baggie in advance (see photo)
- regular paper plate--1 per group on which to build their structure
- books for testing the strength of the structure (I used Geronimo Stilton chapter books)--about 20

**SPECIAL NOTE: You will want to build the structures on one day and then test them the next day. It seems that the gumdrops dry out a bit overnight and become more firm. This will lead to much stronger structures.**

5 minutes

To begin our lesson, I call the children over to our corner to review what we learned in yesterday's lesson.

*Yesterday we tested shapes to see which one was the strongest. Who can tell me what we learned? How did we prove that triangles are the strongest? *

I want the children to be able to connect the ideas from yesterday's lesson to what we are going to practice today. I am hoping they apply the concept that triangles are strong, so it would be a good idea to use them when we build today.

*What shape do you think engineers use a lot of when building if they want their structure to be strong and stable? If you want to build a strong and stable structure, what shape should you use frequently?*

* *

30 minutes

Yesterday the children explored the strength and stability of different gumdrop shapes. In this lesson they will be elaborating on those ideas. I explain the task to the children.

*Today you are going to have an opportunity to use your knowledge of shapes to help you build a structure. You will be given a bag of supplies. This bag has 12 gumdrops and 20 toothpicks. You are challenged to create a structure with only these supplies that is stable and can support weight. Your structure must be able to support the weight of a book. *

I hold up a regular sized chapter book.

*Keep in mind what types of shapes would be the best for this project.*

According to the engineering standard, the children should be able to make a model of an object to illustrate that the shape of an object helps it function as needed to solve a problem. This activity helps bring them closer to achieving that standard.

*You will be working with a partner team for this building activity, since engineers work in teams. I would like you to get out your Clock Buddy paper. We will be working with our 12:00 partner today.*

I like to encourage collaboration as much as possible, so we will be working in partner teams for this activity. To get the children into teams, I use My Clock Buddies. Click here for a short demonstration on how it works.

Once the children have assembled in their teams, I pass out the supplies. I make sure they put their names of the bottom of the plates before they start building. Then I let the children loose to build their structures. Their only guidelines is that they have to use the materials given.

As the children are working I walk around and ask them questions about their work. In this short video clip one child was working diligently on his structure. He was a little flustered that it wasn't stable, so he was adding supports. When questioned, he was able to realize that triangles are part of this support system. Click here to see how his team's improvements looked when finished.

The children love this activity. Click here to see some proud faces. Their designs are so creative. Take a look at sample A, sample B and sample C.

15 minutes

**After the children have built their structures, we let them dry overnight (see teacher's note).**

The next day we pick up on the sharing and testing of the gumdrop structures. The children are so very excited to show off their structures to the rest of the class.

*Each partner group will have a chance to show everyone their structures. You will come up to the front of the room and put your structure on top of this stool. Then you can tell us how you made it and what designs you used in your structure. Then we will test your structure's strength by putting books on it. How do you think we should go about testing it? How can we tell if it is strong or not?*

I want the children to come up with the idea that we should add the books one by one. When the structure starts to fall, then that would show that it cannot hold any more books (see photo).

The partner groups take turns coming to the front to share their gumdrop structures (see video clip). Each time a structure is shared, we look closely at the designs and shapes that the partner team utilized. I really want the children to focus on the idea that shapes, such as triangles, can add to the stability and strength of an object (see video clip).

How many books do you think our strongest structure held? Check out this video clip to find out! This strong structure gave us a great opportunity to reinforce the idea of using triangles.

After the test is complete, I hold up the strongest structure.

*What do you notice about this structure? *

The children look closely and comment that it is made up entirely of triangles. It is an ah-ha moment for the children. Even though we had talked about the use of triangles, they now realize that the more triangles you use, the stronger your structure becomes.

5 minutes

Our wrap-up is super short, since we had in-depth discussions during the sharing/testing phase.

I simply ask the children what they have learned from today's lesson. Hopefully they took away the idea that the design of a structure influences its stability.

The children almost answer in unison, "Triangles are very strong and stable!"

A girl adds, "Engineers use lots of them when building and now I know why."

From what they have said throughout the investigation and now at the end, I think they have mastered the main ideas. Armed with a knowledge of what it takes to build a strong structure, we are ready to move on to our next challenge--building a newspaper tower.