Question 1017215
<pre>
Weighing #1:

Select two boxes, label the lighter box A and the heavier box B.

Weighing #2:

Weigh the remaining two boxes, label the lighter box C and the 
heavier box D.

Weighing #3:

Weigh the two lighter boxes, A and C.  The lighter of these is 
the lightest of all 4 boxes.  

Weighing #4:

Weigh the two heavier boxes, B and D.  The heavier of these is 
the heaviest of all 4 boxes.  

That means the other two are the middle-weights 

Weighing #5:

Weigh those two middle-weights.  The lighter of these two is
the next to the lightest.  The heavier of these two is the
next to heaviest.

Now you have them in order from lightest to heaviest.

Edwin</pre>