A、Criticize him for the lower marks and praise him for the good. B、Praise him and give some suggestions for further improvement.

(35)Research indicates that parents who reward self-control and independence tend to have children with high achievement motivation. (33) Such parents set high standards for their children but allow them to work at their own level and to make their own mistakes. That is to say, they are not very critical. By contrast, parents of low need achievers typically set impossibly high goals for their children and make extreme demands, In addition, parents of high need achievers encourage good performance but do not blame their children angrily when they fail. (34)If a child comes home from school with As and one B on a report card, the parents focus on the As, while not paying much attention to the B; parents of a potential low need achiever tend to ask, "Why the B?" Parents of high need achievers respond to middle grades with warmth and suggestions for reasonable goals and ways to reach them. They can help their children to find a way out. Parents of low need achievers would scold and punish the child. When a child is having trouble with a maths problem, the parents of high need achievers will suggest the general procedure and let the child work out the particular solution; a low need achiever’s parent will solve the problem and then hand the child the answer.
     Closely related to motivation are emotions, which can activate and direct behavior in much the same way as physiological, social and psychological motivations do.