GamesNovatory/Devices/Balances/Weighing

Origin of the Game
The owner of a village general store has a balance with 4 standard weights of 1, 3, 9, and 27 pounds. How will these standards be used to measure every weight from 1 to 40 pounds ?

balance-roberval

The Device
Most kindergarten and elementary classes are equipped with a rudimentary scale,
     the problem being to make the weights, both the standard and the unknown.
We recommend using small containers, like those used for 16mm film,
          the empty container serving as the unit weight.
     Adding plasticene, and later metal washers, to the containers,
          will produce the "3" and "9" standard weights, which will be clearly indicated as such.
     The unknown weights can be produced in the same manner,
          but evidently left unidentified.

Mathematics
This is a question of simple addition and subtraction to make the balance even.

Pedagogy
Start with only the 2 smallest standard weights ("1" and "3")
and the 4 smallest unknowns (from 1 to 4 units),
which the child will be asked to identify and place in order.
Other children can very well watch, offering help and advice as required.

Move on to the addition of the "9" standard weight and the 13 smallest unknowns,
when the children are ready.