Describe the actions that pleased you . The youngsters might be from cultural groups or homes that do not praise children for appropriate behavior. The American middle class home is one of the few in the world that uses this strategy. Youngsters from homes unlike the middle American may be unfamiliar or uncomfortable with the receipt of praise. Maybe the youngsters think that they have accomplished their goals and can now goof off.
Rewards tend to be given after structured tasks.
Unstructured times often follow. In that way, personalized contact gains reinforcing value. Then start to remove the material rewards slowly. Give verbal recognition along with material rewards. That beach scene you've painted is really eye catching.