In an episode on Crayon Shin-Chan, Shin-Chan says
In this situation, he was knocking the door (For the second time he was knocking. His mom has already told him that he should properly say "I'm home", as he didn't use the proper greeting. Shin-Chan replied that "You should not take a child's words too seriously".)
Shin-Chan's mom replies from inside the house
She was angry on him for returning home late.
Jisho says there is this verb 開ける, which may mean
to open (a door, etc.)
But why Shin-Chan uses the te-form of the verb? He could at most use the imperative form of the verb, which is 開けろ.
Another question, why Shin-Chan's mom uses the polite masu-form of the verb with her kid, while Shin-Chan didn't use it with her mom?