Goody Goody Gumdrop! Triangles are so strong!

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SWBAT state that a triangle has more strength than a square based on evidence.

Big Idea

We can prove that a triangle is stronger than a square using evidence.

Teacher Notes

Activity Description

The children will design a very simple investigation.  In their investigation, they will work in groups to create shapes with gumdrops and toothpicks.  First they will form a square and test its strength by pushing on its side.  Then they will form a triangle and test it in the same way.  They will then construct an evidence based account telling which shape is the strongest.

NGSS/Common Core Connections

In this lesson, the students will be asking questions that will help them plan and conduct a very simple investigation.  It will also help build knowledge about the shape of a designed item will influence its structure and function.  This knowledge will give them a solid foundation for when they build their own tower at the end of the unit.  In addition, we will be working on creating an evidence based account.


(click for a photo of the materials)

gumdrops-- 4 per group

toothpicks--4 per group

small paper plate--1 per group on which to build their shapes

Goody Goody Gumdrop science notebook page--2 per child (1 for triangle and the other for the square exploring)

OR Goody Goody Gumdrop regular page--( use this one if you do not want a foldable)-2 per child

Here's a video that explains how to make the foldable.  It's simple to do, but here are some tricks that might help you.



5 minutes

To begin our lesson, I call the children over to our corner.  It is a great place to start a group discussion.

Today we are going to develop a very simple investigation. We have learned how scientists begin investigations.  What do they usually start with?  

Since we have talked about this so much this year, my students shout out that scientists start investigations with questions.  I have tried to make an effort this year to make sure we talk about that concept often.  Answering questions is the driving force behind scientific efforts.  If the children don't remember that right away, you could have them think back to other lessons and activities that they have done in which they learned that scientific investigations begin with a question, such as this lesson called Questions Have Clout.

We need to figure out what shapes are strong, so when we design a tower, later in this unit, that we can use that information. What is a question that we can ask that we could answer with a simple investigation?  Remember we want this investigation to help us with building towers later in the unit, so it should have something to do with shapes and their strength.

 The idea that I want the children to eventually come up with a question, such as, "What shapes are the strongest?"  I write their question on the Smartboard so we can reference it as we work.

In order for you to figure out the answer to that question, you are going to be doing a simple investigation.  I have gumdrops and toothpicks that you can build with.  What do you think we should do with those supplies that would help answer our question?

The children come up with the idea that we can use the gumdrops and toothpicks to build different shapes.  So I have the children partner up with their My Clock Buddies.  I use the clock buddies when I need them to easily get into groups easily.   Click here for a demonstration of how My Clock Buddies work. 


Explore/Explanation with Squares

15 minutes

I give each group a bag with 4 gumdrops and 4 toothpicks. In this way, they will be able to build a square then reuse the supplies to make a triangle.

I want the children to explore the idea of which shapes are the strongest.  The children have come up with the idea that we can build with the gumdrops and toothpicks, but before we start this simple investigation, they are going to have to decide how we should conduct our simple investigation.  

Okay, what shapes do you think that we can build with the gumdrops and toothpicks that I have given you?

I let the children take a good look at the supplies, but they should not take them out of the plastic bag yet.  I know if they take them out, they will be building and not really paying attention to the task at hand.  I don't want them to build yet since we still have the investigation to set up. 

The children come up with the idea that we can make a triangle or a square...perfect!

I want you to first make a square.  How many toothpicks and how many gumdrops will you need to make the square?  

I have the children go on ahead and make the square using the supplies. 

How do you think we could test this shape to see if it is strong?

 They test it by pushing lightly on it (see photo).  It is so interesting to see their reactions.  They are noticing how easily it bends.  I love how some partner groups use science vocabulary such unstable when describing the reaction.  Click for video clip of two girls exploring the idea of stability of the square.

Then I have the children fill out the science notebook page about the gumdrop squares.  They first have to write the word "Square" in the top box.  Then in the next box they need to draw a diagram of the square and label the parts.  In the third box they have to draw a picture of what the square looks like after they gently pushed on the sides.  On the last lines they should write their observations to create an evidence-based account, which is one of the science practices.  See sample 1 and sample 2.


Explore/Explanation with Triangles

15 minutes

Then we repeat the same process with the triangle.  I have the children work with the square first so they can see what it looks like when something is not very strong.  It gives them something to compare the triangle to.

What could you do to make our square into a triangle?  Would we be adding or taking away gumdrops?

The children decide to take away one gumdrop and one toothpick to make a triangle.  They easily form the triangle (See photo of the gumdrop triangle).  

How do you think we should test if the triangle is strong?  How could we figure that out?

They repeat the test by pushing gently on the sides.  It is fun to see them figuring out how strong a triangle really is (see video clip) when they discover that the triangle does not bend at all!

When we finish, the children work on a recording sheet, just like they did with the triangle. I have the children fill out the science notebook page (which is the same as the square page) about the gumdrop triangles.  They first have to write the word "Triangle" in the top box.  Then in the next box they need to draw a diagram of the triangle and label the parts.  In the third box they have to draw a picture of what the triangle looks like after they gently pushed on the sides (it didn't move).  On the last lines they should write their observations to create an evidence-based account.  See sample 1 and sample 2



10 minutes

After the children complete both recording sheets, they cut them out along the outer lines. Then they fold the pages like an accordion (see video in teacher notes).  They glue both in their science notebooks on the same page.  Click for sample 1 and sample 2.  Even though their covers did take a good amount of time, I love how they turned cute!  You really can't go wrong with a gumdrop. :)

After the pages are glued in, I call the children to the front area for a quick discussion.

Which shape was the strongest?  How were you able to tell? What proof do we have? What would be some other ways that we could prove that a triangle strong?

I want the children to take away the idea that we can make observations that will  help us construct an evidence based account.  

Tomorrow we are going to take your knowledge about shapes and build gumdrop structures.  I can't wait to see what you build!