In Gcompris' game Balance the scale the help text says: To balance the scales, move the weights on the left or right side. First of all weights can't be placed on the right side, the program refuses that, secondly move weights on a side should be: move weights to the left side.
Thank you for reporting, it allowed me to find a funny bug where, once you have dropped a mass from the middle to a side, if you click on the previous place where you took the mass, it appears again on the center. I updated the string to: "To balance the scales, move the masses to the left or the right side (on higher levels)" because we can drop on right side starting level 4.