Dead Thomas, who had been sitting with his mouth hanging open, gazing out of the window, jerked out of his trance; Lavender Brown's head came up off her arms and Neville Longbottom's elbow slipped off his desk.
Proffessor Binns blinked.
Assuming 'Dead' was a mistake, there's nothing
tell about this. It's a perfect example of
showing the student's boredom.
Tell would be...
Thomas was bored out of his mind. Lavender was so bored she had fallen asleep. Neville was bored too and kept being clumsy.
JK
showed us them being bored, with Thomas gaping and staring out of the window and Lavender laying on her arms. We
see that they are bored, without being
told what we're shown.
Proffessor Binns was looking at her in such amazement that Harry was sure no student had ever interrupted him before, dead or alive.
This on the other hand is
tell. We're not shown Binn's amazement etched on his face, but instead we're
told so by the Omni narrator. But it's not bad, because we're inside Harry's head and that will usually be
tell. Interior monologue = tell.
That's not really that true though. It's best to think of Interior Monologue as being exempt from the rules of
show and tell. At least that's what I do...
Though the danger with Interior Monologue are possible info-dumps...
But that's off-topic, so anyway...
Showing, in the show
and tell sense, does not mean you can't mention what is happening or that you have to use flowery language. It means that instead of simply describing what's happening in bland factual statements, you
show them.
Tell:
John bullied the kid in front of him.
Showing:
John tore off tiny bits of paper and chewed them up until they had just the right consistency. Then he flicked it at the boy's head in front of him.
Bored, Angry, Tired, etc. These are all words that can either be used to
tell (John was angry), or you can expand on them to
show your characters going through those emotions (John threw his book at the wall).
If your MC's dad is angry at her, he's going to
show it through his actions and dialogue. He's not just going to say
I'm angry. He may stomp and shout and snatch the MC's phone away.
But even then, there's no problem with
telling in itself. If for instance your characters habits and personalities have already been established, then there may be nothing wrong with simply saying "John was bored".
This is something you're going to have to judge on your own when writing. There are no rules, but there
are techniques which work and don't work.
If John just crashed into a mailbox, you might want to
show the anger of his parents as opposed to simply
telling us they were angry. The morning after, you may get away with John thinking to himself or having him tell a friend that they are
still angry with him.
It's all about proportion.