Practicing the Invisibility Spell

He tossed the fireball upward. Orange-red flames immediately engulfed him. Snape leaned back slightly and drew his Wand, but an utterly calm voice came from within the fire. "Professor, I'm fine!"

As soon as he spoke, the flames swirled into the space between his brows. Seconds later, the black-haired, dark-eyed boy stood there smiling, as though he had never been on fire at all.

Snape paused for a few seconds, then put away his Wand and walked calmly to the Bookshelf. He picked up a jar containing a specimen. "Ridge-Scaled Green Snake. Highly venomous. Its venom attacks the nervous system; a single drop can bring down an ox. Robin Sear, listen carefully. Summer vacation is not for playing around. Even if you came first in your year, you still need to learn new things over the summer, or Hermione Granger will soon catch up with you. Take this specimen home and study it carefully. Oh, and take this Ridge-Scaled Green Snake Antidote in case you need it."

"Professor, I came first in my year?"

Luo Bin certainly knew how to pick out the important part. He raised his eyebrows as he asked.

"Robin Sear, you came first not because you're exceptionally talented, but because your competition was hopeless..."

Uh-oh. He's angry!

Clearly, joking with the stone-faced professor was a bad idea. Luo Bin quit while he was ahead, cheerfully praised Snape a few times, then pocketed the antidote and left the Potions Storage Room carrying the specimen jar.

"Listen carefully. Before you report back on September first, I expect a ten-thousand-word observation and research report on the Ridge-Scaled Green Snake!"

Ten thousand words? Was that any way to talk to someone?

Luo Bin had a reasonable suspicion that his joke had prompted Snape to add another five thousand words. He