Offering rewards to try to motivate behavior we want is EXTREMELY common in our culture – from promising a toy for going to the dentist, to money for reading books. (This practice extends well beyond childhood to the corporate world and beyond.)
Unfortunately, large amounts of research has shown that rewards do not work to build motivation for a task. In fact, they are counter productive. Study after study has shown that people become *less* motivated to do something after receiving a reward or incentive than they were before. (Kohn 2010) This applies to attendance, school work, acts of kindness... all the things that we want to encourage! When people receive rewards, they seem to conclude that they were doing the thing for the reward, and loose inherent motivation to do it.
Instead of linking money, treats, bribes, prizes, or other rewards to behavior we want, offer connection, repeat what your child must do, and explain the reason. Stay clam, connect, and repeat.