They can't tolerate failure.
As first graders strive to become more independent, they become highly concerned with their personal behavior. Tantrums can occur if your child accidentally breaks something, if she can’t solve a problem, or if her peers outperform her in school or play.
What you should do: Be patient and understanding. Accept this as a normal stage in your child’s life. Remind her of things she’s learned to do in the past year, such as riding a bike, doing dishes or reading.