When we talk about balance we refer to two or more equivalent forces acting on an object in opposite ways, so that it mantains its state, this is called balance of forces.
On the other hand we talk about unbalance of forces when the involved forces are not equivalent.
The most common demonstration of balance and unbalance of forces is the action of two or more weights, or weight forces, on a scale.

This simulator helps the students concretely visualize the state of balance and unbalance of forces through the use of weights on a teeter totter.
The simulations are divided in three sections for a gradual and clear comprehension:
practical introduction example with everyday objects as weights; a more technical lab, to concentrate on the weights proprieties, proportions and relationships; and a fun game with a scoring system to challenge what the students have learned.


  • Understand how positioning and moving objects on the plank affects its movement;
  • Predict how objects of various masses can be placed to create balance;
  • Solve puzzles about balance and unbalance;


  • Create three different sistuations where the plank lifts on the left and three where it lifts on the right;
  • For each situation change weights and distances on the left to create balance, then do it on the right;
  • Write for each situation of balance and unbalance the proportions between the variables and deduct the general rules behind them;
  • Test what they have learned about balancing in the final game.