Sample Module 1 task

[Steve Cates]

In thinking about module 1, I thought that developing the formula for triangular numbers might be too ambitious.   The standards talk about developing a formulas for linear and exponential models but not quadratic models like we have here.  I don't want to throw it out because I believe it is a good problem, but perhaps we should lessen the blow by working in the square number example in the introduction or providing some intermediate steps (?)

Anyway just my 2 cents.