First/then boards and icons provide children with a visual representation of Premack principle. Through the use of this contingency, children start to understand that reinforcement is available following a less preferred activity.
Premack Principle, which is also known as “grandma’s rule” or “first/then language,” occurs when a preferred activity is used as reinforcement for a non-preferred activity. It is an easy way to increase motivation and provide access to preferred items (reinforcers) in a controlled way.
Make sure that your child (or student) completes the “must-do” task BEFORE, gaining access to the reinforcer. It is also essential to ensure that the reinforcer is something the child REALLY wants. It will stay powerful by limiting free access to it.