For operant conditioning the first thing that comes to mind that most kids have been through, and that is getting paid to do chores.
Simple case of kid does chore, kid gets paid. This would be an example of positive reinforcement. It gives the kid something positive such as money for doing his chores. This guarantees that his behavior towards chores should get better over time. It similar to adults going to work every day to get paycheck at the end of the month. With the kid he gets paid after doing his chores and eventually when they grow up they will do their chores without that reward, making it a fixed/variable consequence
schedule.