My child's teacher says he cries a lot over minor things at school. Preschool to 3rd grade Children need to be able to cry and work through their feelings as they go through life. Let the teacher know that you're not worried about your child and that if he's allowed to cry he'll get over whatever's bothering him. If it's not okay for your child to cry and get upset in school, arrange a bit of extra time in the morning and after school to check in with him. This gives him a reliable time outside of school to get his feelings out.
Young children face challenges and disappointments all day long.
Our society is not set up well for parents and teachers to give children the space they need to express feelings. The result, for many children, is that small things, like spilled milk or a broken cookie, can bring up all the disappointments of the day. Your child's pretext for getting his feelings out may seem trivial and silly, and his response may seem beyond what the situation merits. But understand that children are good at using small upsets to help them express feelings about bigger things. If the teacher understands this too, she will be less worried that a child is overreacting to a minor frustration.