Academic ability is different than emotional development & comprehension and it does not develop at the same time.
It is not congruous.
He is 3.5
Their emotions at this age are not even fully developed yet. Kids do not have automatic skills and ability about coping-skills either nor the automatic instincts for it. Nor is their communication or social skills fully developed yet.
The whole person, is not developed yet.
Kids do not know how, to discern or analyze their emotions nor the abstractness of all social situations nor do they even have the ability to have self-reflection or have deductive or inductive reasoning, yet. They don't know how to handle... being Frustrated. Even some adults don't know how.
They are also still learning boundaries/right/wrong, and the domino effect of their behavior upon themselves and others. And they also do not have fully perfect impulse control yet, nor are they experts at the nuances of tones or voices or how to express their feelings nor the full knowledge of the names of the many feelings that are developing in them.
All of these aspects, are still very not developed yet.
It is learned.
3 is a hard age.
And 4 is hard as well.
No is no. Do not argue with him or try to explain why in lengthy explanations. Say no. If he tantrums... then repeat it, then sit down and read a magazine. Tell him when he calms down.. THEN to tell you. AND you then convey to him that flipping out like that is not appropriate and that he STILL needs to learn.
Kids... WILL deflate on their own. If he is in a tizzy, just disengage and tell him no, you will not argue or fight about it. His tantrum will not get him things.
Once he learns, that you will not engage in his tantrums and that ONCE he calms down... then you will converse with him. Have him apologize as well.
Just punishing/taking things away from a child will not make them, better. It ALSO has to involve, in tandem... the teaching of skills to help them cope. So that in time, they can self-manage better and know, how.
Role play with him.
Teach him words to use, ways to say things if frustrated etc.
I taught my kids those things since they were 2 years old. By 3 years old, my son could tell me how he felt and the differences between him being "frustrated" "grumpy" or "irritated." He could actually tell me and knew how to know, himself. And to know how he feels and how to help himself feel better, with having "teamwork" with, me about it.
He'd tell me things like "Mommy, I'm grumpy, I'm going over there to be by myself." And then once he felt better, he'd come and tell me "I feel better now..." and hug me. I never scolded him for that. I was proud of him. If I told him "are you grumpy?" he would say "No Mommy, I'm frustrated..." and I'd ask him why. And he'd tell me why... like he is frustrated that he can't find his toy etc. Then we would problem solve that, TOGETHER.
Teach him to "try your best...." not being perfect.
To try, HIS best. Then compliment him when you notice he is, trying.