20 Pointed Star {Icosahedron} Part Four

This post is part of my Stellated Icosahedron Straw Project. See part one ,  part two, and part three first.

In this post, I’m going to show you how to make the center of the 20 pointed star. It’s a 20 sided figure (Icosahedron). Beware that there are lots of pictures!
SDC19557To start, know that you should use only one color on this part. The 20 pointed star looks best if the icosahedron is all one color and the stellations are another.

Let’s get started!

Step 1: Take your long strand of ribbon and place five straws (note that I’m referring to the half straw pieces when I say straw!)
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Step 2: Tie it together to make a pentagon. Note: Make sure every time you tie it, it’s a double or triple knot and is very tied well. DO NOT DO THIS FOR THE STUDENTS! Students will ask you to tie it for them, DON’T! Make them figure it out and be independent. Plus, you’ll go crazy and waste bunches of time if you have to tie it for every student.  Another note: leave a tiny bit of wiggle room in the pentagon, you don’t want the pentagon to be stiff. It should wiggle (a little) with ease!
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Step Three: Cut off the pentagon from the ribbon and repeat step two but don’t cut the second pentagon from the ribbon this time.
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Step Four: Pre-build the next figure (steps are below) and show the students that we are transforming the two pentagons to look like the next figure. I usually place it on my wrist and say it looks like a giant bracelet. I try to have them see the patterns and have them give me the next steps with out telling them, this helps them visual the next step because the next step is the hardest. Doing this makes it easier for the students to visualize the next step in their head. To help guide them, I sometimes put the two pentagons in the air with one a little above the other and have them imagine how to make it look like the prebuilt figure.
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Step Five: Put a straw on the ribbon and bring it all the way down to the pentagon. You will then attach the other side of this straw to the other pentagon, which connects the two pentagons. To attach them, you don’t have to tie a knot each time (that’s very time consuming). Instead you can wrap the ribbon around each vertex, if you do this method instead of a knot, make sure to wrap it tightly and twice (that’s what I do!). You’ll need to keep one hand on it so it doesn’t come undone at first, but once you start the following step, then there is no need to hold it any more because the next step keeps it together.
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Note: Make sure that you are wrapping the ribbon around the ribbon, not the straw:
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Step six: The next couple of steps are very similar. Place another straw on the ribbon, bring it down to the pentagon, then connect it back to the other pentagon. This creates a triangle connecting the two pentagons.
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Step Seven: Place another straw on the ribbon, bring it all the way down to the pentagon and connect it to the other pentagon. Notice how the pentagons start to become tighter each time. This is why we left wiggle room in the pentagons.
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Step Eight: Place another straw on the ribbon, bring it down to the pentagon, and attach it to the other pentagon. Notice how the pentagons are even tighter now. At this point, we need to make it ‘pop up’ and be more three dimensional.
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Notice: the two pentagons are basically on top of one another and the individual straws we added are starting to zig zag between the two pentagons.

Step Nine: Keep adding one straw at a time and finish ‘zig-zag’ around the two pentagons.
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Ta-Da! You made it all the way around. That was the hardest part and usually ends the second day of the project. From here on out, it’s easy! 🙂

What we have so far is what I like to describe as a large bracelet. I usually stick my arm through it two show the students where the two pentagons went to in the project. To finish the icosahedron, we have to fill in these two pentagons.

Step Ten: Add TWO straws to the ribbon. Attach the ribbon to an adjacent vertex of the same pentagon:

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Step Eleven: We want to use the triangle that those two straws created to help fill in the pentagon. To do this we need the ribbon to be at another vertex. Feed the ribbon throw the edge/straw to get to the next vertex:
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Step Twelve: Add a straw, and attach that straw to the triangle.
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I turned over the project to make it a little easier to work with:
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Step Thirteen: Add another straw (which will start at the top of the triangle) and bring it down to the pentagon.
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Step Fourteen: Only one more straw is needed to fill in the pentagon! Before you add that last straw, feed the ribbon through to get to the next vertex of the pentagon:
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In this picture, I’m adding more ribbon by just tying two ends together, but you can see the completely filled in pentagon in the background!
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Five straws go from each vertex to meet at one point to fill in the pentagon. No more hole on that side! But now you have to turn it over and do the same thing on the other side.

Repeat Steps 10 through 14 to fill in the other pentagon. You’ll notice that you will need the ribbon to be on the opposite side of the project. You can either tie a knot, cut if off, and reattach it to the other side OR you can feed the ribbon through the straw to get to the other side:
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Pictures showing Steps 10 through 14 repeated:
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Wahoo! A completed icosahedron! 🙂 At this point, I’m usually in the middle of day three and show the students how to create the points. Some figure it out on their own though! Make sure to tie off the ribbon you are working on and cut if off. You’ll reattach a new color ribbon for the points.

As a side note, I want everyone to know that I have mastered typing long blog posts while covered in dogs. Yes, covered in dogs:
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I enjoyed it. 🙂

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One thought on “20 Pointed Star {Icosahedron} Part Four

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