public void handle(ActionEvent e){
            if(e.getSource() == mechanicsChoices[INDEX_TWO] || 
                    e.getSource() == wavesChoices[INDEX_TWO] || 
                    e.getSource() == electricityChoices[INDEX_TWO]){
                JOptionPane.showMessageDialog(null, "UNDER CONSTRUCTION");
            }            
            if(e.getSource() == mechanicsChoices[INDEX_THREE] || 
                    e.getSource() == wavesChoices[INDEX_THREE] || 
                    e.getSource() == electricityChoices[INDEX_THREE]){
                mainPage.setScene(mainPageScene[INDEX_THREE]);
            }
        }