var current_tb_iter = 0;
var smi_0 = window.setTimeout("swap_menu_images(0);", 2500);
var smi_1 = window.setTimeout("swap_menu_images(1);", 5000);
var smi_2 = window.setTimeout("swap_menu_images(2);", 7500);
var smi_3 = window.setTimeout("swap_menu_images(3);", 10000);

function swap_menu_images(id)
{
    switch (id) 
    {
        case 0:           
            swap_menu_image( $( 'tb_lowerschool') );                        
            break;
       case 1:
            swap_menu_image( $( 'tb_lowerschool') );                        
            swap_menu_image( $( 'tb_middleschool') );                        
            break;
       case 2:                                   
            swap_menu_image( $( 'tb_middleschool') );                        
            swap_menu_image( $( 'tb_upperschool') ); 
            break;
      case 3: 
            swap_menu_image( $( 'tb_upperschool') ); 
            break;
    }    
}