That’s a great story. I did that cigar box thing back in the 60’s but forgot all about it until you mentioned it. I also recall that I loved that little experiment. Do you do this in a science class or what class?
The weight of the empty box is written on the outside. The kids must use the triple beam balance to determine the total weight and then calculate the weight of the objects in the box. It not only helps them reinforce math but helps reinforce the metric system that I have just gone over with them.
The kids really get involved, determining the number of objects in the box. Some even calculate what the weight of each individual object is (I tell them ahead of time that if there is more than one object in the box, they are all the same thing)
It is one of the kids favorite labs of the year.