Waiting in line is a skill that can be taught to children of all ages. There are many ways to do this, but one of the most effective is to model the behavior yourself. When you are waiting in line, make sure to stand still and not fidget. Explain to your child that this is how we wait in line. We stand still and wait patiently for our turn.
If your child begins to fidget or whine while waiting in line, gently remind them of the rules and encourage them to stand still and be patient. It may help to set a timer for how long they need to wait, so they know when their turn will come. Praise your child when they display good behavior while waiting in line.