Have all the objects be the same except for one. Vary the challenge - make them all the same category except for one. Make them all the same shape and color but one is a different size. Sometimes, I have the counter count the children as well and then ask if there are enough objects for everyone. When we have other things to accomplish, we simply count and then put the box away for next time.
Many preschool teachers have shapes or symbols on the floor for lining up.
All of the pockets are on the wall near the door. At line up time, they go and stand on the color they chose for the day. During our unit on trains, we added a caboose and made sure that the last space on the floor was red. You could use shapes, symbols, or any other concept you want to reinforce. The older ones have pockets with their names written on them.