Reflection from February 3 class

Let me start off by saying I never built with blocks as a child, nor have I constructed anything in my life.  I also am terrible about reading through all of the directions ( I hope I am not alone in that!).  So, my tower is a sad affair to be sure.  However, I did get it to support all seven marbles.  I could have saved myself some straws, I used four too many.  The height of my tower was 8 inches.  It did hold all seven marbles and it was constructed using all but three of the straws.  The equation I believe was to take the number of unused straws and multiply that by the height of the tower minus 5 all to the power of the number of marbles held.  So,  (3 straws unused) * (8 inches - 5 ) ^7.  
(3) * (3)^7 = (3) * (2187) = 6,561.
What should I have done differently?  Well, not waiting until my age to decide to really look at construction would have helped.  I also should have taken a few moments to read the equation to see how to be more successful.  Third, I could have removed some of the straws once I realized that they didn't serve a purpose.  I did like the stability of my triangular shape.  It actually was pretty stable and I could support a pair of scissors and a small stapler before it toppled.  The weak spot was the left hand corner because the joint wasn't secure and I should have added a triangular support system around the center of the tower to keep it from twisting.
I will add that there were several fifth grade boys in my room watching me construct this tower, and they really wanted to grab the straws and do it for me.  They were not impressed but offered me "better luck next time" encouragement.