They are dramatic.
The emotions of a third grader can be all over the place. One minute, they’re being affectionate and cooperative with friends, and the next, they’re bossy and demanding. They exaggerate and say things like “Times tables is the hardest thing ever!” or “I hate all the kids in my class!”
What you should do: Be patient and supportive. Expect unexpected complaining and whining. Set limits that allow for some negative emotions while teaching your child self-control.