Don't fully guide the user for unbalanced equations
(by Robert by email)
Have you considering having a setting where the player is not guided so fully as to how to rebalance the equation? Maybe some visual sign that it is unbalanced and then the player has to decide where to put objects to rebalance it before they can proceed? I suspect that players may end up not really thinking about the steps necessary to balance - they just stick the object in the places that are highlighted by the game.