Why is the tower leaning?

30 minutes and my lack of creativity, not a good combination.  I found myself faced with a pile of materials and no plan.  So, I did what I do best, I started and let the momentum take me where it went.

I decided to build a tripod, as a triangle is the strongest shape.  I slide the tops of the straws together creating slip joints at the top for the load area.  Then I created nice strong triangular structure on the side.  Please notice that I wrote side.  By the time I finished the first side, I realized that I was down ten minutes already.  So the other two sides received horizontal cross braces but not diagonal cross braces.  

After I built the first top section, I realized that my tower was not tall enough.  So I "shoved" three straws into the legs to create a taller tower.  I decided the best way to strengthen the tower was to use copious amount of tape (sort of like some people who wrap some Christmas gifts)

Now the problem of how to get the marbles to balance on top of the tower.  I ended up taping small straws in the center of the triangle with other straws as edges.  

I was able to place six marbles on the top.  

I had 11 left over straws from my building.  

My tower, at the point that the marbles are sitting was 10.5".  

Final score 

11 x (10.5 - 5)^6 

11 x 5.5^6

304,487.0469

My tower would hold something heavy, it wouldn't break, it would tip.  My bottom three legs are not even, it would just take a clip of the scissors to fix that problem.  The taped tower will hold up to a baseball (not a bowling ball, I don't think I could get it to balance).  What finally destroyed my tower, the demise of my piece of work?  My two and half year old grandson grabbed the tower off my desk and started to pull straws out of the slip joints.

What would I do different if I had the chance?  I would get those legs even on the bottom and I would extend the holding sides, on top, out further.  I probably would be able to hold the seven marbles.  If I was teaching this lesson I would probably provide the students with a materials list and an idea of what the project would involve.  Then I would ask them to sketch a drawing (hopefully to scale) before I actually gave the materials to build.  I do believe that the 30 minutes of building would be long enough. 

Overall view of the assignment.  I loved it, after I was able to get over the initial "block" that I encountered.  It was wonderful to have a class where I felt like I was actually participating.  Usually I sit in class and grade papers or crochet, not in this class, I have to (and want to) pay attention.