Quote:
Originally Posted by
XanaSnape 
"EXCELLENT! You all are thinking about not just the fact that the ingredients are called for, but considering what they actually do. Every ingredient in a potion has a specific reason for inclusion... Be it to cause an emotional change such as glumbumble, lovage, alihotsy, jobberknoll a physical change, such as accompanies dittany, murtlap essence, mandrake, or a change to the actual process or qualities of the potion: fluxweed enacts change, peppermint tames the harshness of a potion's effects, and thickening the potion with flobberworm mucus actually extends the life of the potion and also extends the length of time the potion will be effective for the drinker." Kazimeriz nodded, drawing his wand with a sharp upward flick , sending a gold star up to hover above the head of each student who answered.
"It seems you are all capable of understanding the basic concept that ingredients have specific effects that they cause within the potion- some work independently, while some work in concert with others... For example, if you have a potion like a calming draught, a tiny droplet of glumbumble fluid is used but is balanced with an alihotsy leaf-- keeping the drinker from becoming depressed."
Kazimeriz began to pace-shuffle around the room, his cane making sharp clomping sounds on the stone floor.
"Now, let us speak more about process. You all know that alternating directions in stirring, at the proper stage in a transformational potion, helps to infuse the potion with your intent for change. For example, if stirring your potion in a clockwise direction is used during some stages of potions for potions that enact a positive change, so what would stirring counter-clockwise likely do? Can anyone venture a guess as to what other brewing techniques might cause specific effects, and speculate as to what the effects might be?" ooc: Again, there is less absolute right-or-wrong here, so feel free to be creative in your answers; speculate and get imaginative like whoa, keeping an eye toward known canon and what seems feasible within the wizarding world that we DO know. 
If you have questions you can also always PM me. 
Celandine blinked slowly, trying to process all this. She'd remember it and sort through it in her head later... but for now...
Cela raised her hand again, "I don't know if I'd say counter-clockwise stirring enacts a
negative change exactly, since usually when you do that you are intending for the change to have negative effects which for the potioneer is a positive change really." Celandine hesitated, hand still raised, "But counter-clockwise stirring helps with brewing any 'undoing' potions, like antidotes. Potions that are used mostly to fix or negate symptoms or effects that the intended taker is presenting."
What else was in the textbook?
"Tea! Tea is a good example of how different brewing techniques can apply; whether you are brewing an infusion or a decoction it can change how strong the resulting liquid is and whether or not the original material can still be used for other purposes or if it will disolve and break down. An infusion is when the material you are brewing is stro... more potent and releases its active ingredients more readily and you tend to add the boiled or hot water or oils to the materials and let it steep, whereas a decoction is where you add the materials to the boiling liquid and keep it on the boil to release the active ingredients, you boil the liquid down and often end up with a more syrup-like result than you do with an infusion."
There was a bunch of stuff about doing that with different poisons and antidotes written in her margins but Cela didn't dare repeat any of that stuff and she didn't have the book in front of her anyways.