"Dolores, what a pleasant surprise," Diana gave the woman a rather fake smile. "Don't mind me, do go on," The woman said and Diana just nodded and continued her lesson.
"So as I was saying, the goblin rebellion of 1752 occurred in England. This was the cause Albert Boot, resigned as minister of magic. He was-"
Aghem.
Diana ignored her. "Minister of magic from 1747 to 1752, its important you note that down, it's a very common question," She pointed out and the scribbling of quilts was heard.
Aghem.
Diana withheld the urge to roll her eye. "The next minister of magic was Basil Flack, he managed to uphold his title for two months, he resigned after the goblins recruited werewolves,"
Aghem.
"Excuse me, do you need a glass of water, Dolores, your throat sounds rather sore," Diana turned to the woman who looked ready to explode.
"No, thank you," She said. "Great, then I can contin-" but she was interrupted.
"It did however, catch my attention that you're teaching history of magic. Aren't you a Astronomy teacher?" She asked with a small head tilt.
"You are correct with both those statements, but, this is not an astronomy lesson, this is a homework hour and my class happens to be struggling with history of magic, so that's what I'll be teaching them," She explained through gritted teeth.
The class was rather enjoying this turn of events, happy something interesting happened so they could talk about it to their friends at lunch.
"And this implies with all other classes?" Umbrige asked and Diana nodded hesitantly. "Yeah, is there a problem? I'll teach anything my students are struggling with." 
"Even, Defence Against The Dark Arts?" She questioned and Diana nodded. "Yes? Why wouldn't I? If a students is struggling with a spell or whatever, I will help them learn it," She clarified.
"See, that's where you're wrong, I teach Defence Against The Dark Arts, and my students don't need to do the spells, just learn them. I think you could better leave that to me," Umbrige said, matter of factly.
"Well that's rather stupid isn't it?" Diana shot at her, she already knew this was going on, now she could finally say something about it. "Excuse me?"
"Aren't you the teacher? Shouldn't you prepare them for the exams? For the world?" She asked and Umbridge made a humming sound. "There is nothing dark out there that they would have to prepare for." 
Diana took a deep breath and nodded. "After Flack resigned, Hespaestus Gore became minister of magic, he still sat at the end of the war, though many do not agree with the way he handled it with the werewolves,"
Umbridge scribbled something on her clibboard and left after a while.
After the lesson, Diana let her students out to get too lunch and was later joined in her classroom by three guests.
"Well, well, well, if it isn't professor Sardothien," 
"or do we call you professor Potter now?"
"Or even better, Professor Black!"
"I liked Andy better," She said making the twins grin. "Andy it is!" The two of them said in sync. "Though, we really do need to talk about that." George said.
"No we don't!" Pippa disagreed. "I have something way more interesting," she stated with a grin, grabbing a chair and taking a seat.
"Do go on," Diana said as she put an E at the top of someone's Herbology test, having promised Pomona she would grade them for her.
"Harry is going on a date with Cho Chang for Valentine's Day," she revealed, the lack of reaction from the twins, let Diana know they where already aware.
A small smile appeared on her face as she looked up for the first time since they entered. "He is now? Where are they going?" She looked at the girl and then turned back to the tests.
"Oh, he's taking her to Hogsmeade, she wants to go to madam puddifoots," she explained. "No idea what that is though,"
Diana halted and looked up once again. "Madam Puddifoots?" She asked for confirmation. "Yeah!" Pippa said and then frowned at the weird look on her mothers face. "Why?"
"It's... rather interesting, I suggest you do not ever go there- it's horrible," she said shaking her head.
She didn't notice the look the three kids exchanged. "Now, I'd you don't mind, I have papers to grade, and you have classes to attend. Chop, chop," 
The kids left with smiles on their faces, ready to speak of their plans, outside of this classroom.