It is difficult for an illiterate worker to use a beam balance too
because the worker may not know what denominations of weights to put in
It is easier for an illiterate worker to use a digital scale because it
shows the numbers. You can print all the weights on a paper, give it to
them and ask them to put the material until the number in the paper
matches the number in the meter.
In a beam balance, once a supervisor tells them which weights to
use, their job is easy.
With a digital scale, it is not as easy as you make it sound. Let us say
the workers are supposed to pour 5.3 kg of material. They pour a
little too much material and the scale shoots up to 6.2 kg. Now
they don't know whether they should keep pouring more material or remove
The digital balance has to be designed in such a way that a given weight
can be preset. When the worker fills the bucket and the total weight
reaches the preset value, the digital balance can alert the worker
either by showing a green light or by beeping. The worker must be able
to notice this alert and stop filling more.
Your solution would work fine if the factory had some control on the
design of the digital weighing scale. However in this case, the factory
has no control on the design of the digital weighing scale. They have to
work with what they have. Therefore your solution will not work in
Here is my solution: Most digital scales have a button called "Set to
0". Let us say I want the people to weigh 5.3 kg. I keep
5.3 kg weight on the scale and press "Set to 0". After I remove
this weight, it shows "-5.3". Now the worker only needs to pour until
the scale shows "0.0". The worker just needs to know "0" to do this. To
know whether to pour more or remove from the balance, the worker just
needs to look at the "-" sign. If it is there keep pouring, else remove.
:-) So the worker can achieve the task by remembering "0.0" and "-"
Your solution is pretty much what I had in mind too. I proposed this
solution to the factory management and it was successfully implemented
in the factory. I have updated my blog post with these details. Thank
you for participating in this discussion and offering your solution.