Getting girls at school sucks, especially starting with little reputation. You should be spending time with friends outside of school. That leads to a happy existence, which leads to confidence, which leads to getting pvssy.
If I was in your situation I would try to get into a clique with some people who you could watch interact with the type of chicks you like. Context is a beautiful thing.
If you choose not to go the context route the only advice I can give is:
In sports, the defense is REACTIVE, the offense is ACTIVE. Now think about how those two interact. By going on the offense (or actively affecting someone's emotional state through conversation) you make them reactive to you. Now they're predictable and conversation should be easy. All you have to do is keep them under an exciting emotional state and they will love you for it because before you took charge and made their lives interesting they were sitting their bored, unaffected. Its truly that easy. Emotional state = exciting.
For whatever reason people usually suck at being reactive AND active, so you should get good at doing both in conversations. This way when you approach someone to start a conversation (which inherently involves you affecting their emotional state so you can get their attention) your offense is game, when someone turns the tables and goes offense on YOU, the same can be said about your defense AND you get the ego boost that they're taking the time to affect you, actively. That can only lead to more entertaining conversation.
Your goal is to affect her emotional state so masterfully that eventually she is inspired to affect yours. And it matters little how she tries to affect your emotional state! Imagine she tries to make you angry! If she does, then you should be able to reactively, masterfully counter by again affecting her emotional state through laughter, anger, w/e.
As long as you're continually affecting her (i.e. appealing to her emotions) a conversation is a living thing. Otherwise, it's a dying thing.
Since you don't have the confidence and reputation as a pimp daddy, yet: YOU have to approach chicks with the idea you're trying to get them to affect YOUR emotional state by affecting their's.
Let's take your Daniellle example and apply my advice.
First, lets remind ourselves of the original:
[I tap her shoulder lightly 'to get her attention' and go "Hey Danielle."]
Danielle: Uh, hey Mike.
Me: So you going to the carnival this Saturday?
Danielle: Uh, no I don't think I'll be able to go.
Me: Oh, well, that's cool.
Danielle: Yeah.
Me: So, uh, did you take the Algebra test yet?
Danielle: No, not yet .
Me: Oh, well, it's pretty easy. You'll do good on it.
Danielle: Uh, thanks.
Me: Well, see ya later.
Danielle: Bye.
Now, if you had been a MAN and took responsibility for her emotional state (i.e. keeping her entertained) during the conversation, it probably would have gone something like this:
[I tap her shoulder lightly 'to get her attention' and go "Hey Danielle."]
Danielle: Uh, hey Mike.
Me: So you going to the carnival this Saturday?
Danielle: Uh, no I don't think I'll be able to go.
Me: Oh, well, that's cool.
Me: Say, I hear they're going to have a destruction derby in the circus. I signed up. *quick inhalation of breath, followed by a mock "Yep".
*eyebrows crinkle*
"Have you seen my car???"
Danielle: *laughs*
"Sorry, I don't remember your car but one of my girlfriends said it was a junk heap"
Me: Yes, yes it is.
Danielle: *laughs*
Me: What do you drive?
Danielle: I don't, my mom is all pissed at me for blablablabla.
Or further on in the conversation you could have:
Danielle: Yeah.
Me: So, uh, did you take the Algebra test yet?
Danielle: No, not yet .
Me: Oh, well, you're screwed. Its not easy at all, and the test is literally *one* multiple choice question.
Danielle: Really?? I didn't hear that!
Me: True, see its basically the Algebra teacher, Mr. Murdock's life story.
*thoughtful look*
"I never knew you and he dated! Isn't that illegal?!"
See how the setup transitions into the punchline? The setup works because right then she's AFRAID of failing the test, so you have her attention, then you transform her emotional state to laughter right before her eyes. What chick isn't going to dig that?
Just remember, good looks are relative, and matter little when you can have the courage to dazzle people with conversations. They KNOW you're controlling them through appreciable entertainment, and they DON'T KNOW HOW. They may as well think you're a god.
Further on in your progression you may want to take a second look at this, because you'll notice if there's a girl that understands how the game is played, and she can play it just as well, (i.e. stress you out) she's probably a keeper.
But yeah, this
very specific advice can only take you so far. There's a danger you get so good at it that you're talking for hours and never actually do anything, etc.
Since it's High School, you're in an institution with STRONG cliques, so infiltrating one of the cliques and seeing how they get chicks is probably your best bet. That's basically what I did. Its harder for lone wolves of any kind to get laid in high school. See, when you get older and get a good job, these strong cliques don't exist so much because #1: People change jobs so much and #2: We're adults, we're supposed to know that reacting based on a clique mentality is retarded.
Be careful because not only do you get good context, social experience, and social proof out of those cliques, oftentimes you absorb some of the bad things, too.