Let's say this girl is HB7.5 . I met her once after a highschool basketball game and just walked around with her friends and one of my buddies and talked to her for literally hours. So then in chem the first thing we talked about , well after class i asked her what she did after i left her and we've had small casual mostly just hey or hi. The other day the teacher called her group over to see my groups project and she comes over nudges me jokingly and starts comments on the project. all i really could say was "Yeah , I didn't really like doing it " . And she ussually trys to talk to me when everyone is just hanging out when the bell is about to ring but sometimes i don't manage. But what im kinda sensing is she isn't really interested she just expects us to talk after that night . And Oh yeah there is 5 days left in semester so i need something quick .
And what bugs me is she asked me for my number that night but my parents had taken my phone and couldnt give it to her but now that i have it back , i don't want to ask for it as it doesn't seem as casual in school. she also talked to me on facebook the day after.
Thanks for any insight.

What should i tell her when everyone is just chillin lining up at the door waiting for the bell to ring . should i just start it by being like Sup ___?

Just invite her out with you. Is there another basketball game coming up? Especially if its an away game where you can pick her up and take her to it - you should also know other people going as well (dont show that youre going out of your way for her). Having someplace to go and something to do, and just inviting her to tag along makes it more natural, and gives you an excuse to grab her digits - "here put your number in my cell so that I can call you with when I'll pick you up".

And as far as the semester ending, its no big deal - as long as you get her number before the class is done. If you've got the digits, and no longer have class with her you have an excuse to call her up - "Hey, I haven't seen you since chemistry class, me and a couple buddies are going to [wherever], you should come along"

My biggest advice to you is to start showing some initiative. By the sounds of it, she's starting all your conversations. Women expect men to lead, and this especially applies to starting and maintaining conversations. High school is more about social proof than anything else. Show her that you're fun, you keep busy, and as stated before, willing to take the lead, and you should be set.

Hope it helps,
~GQute

PS - One major point. If you invite her to an event that her friends arent initially attending already, and she doesnt bother to invite them along, take this as a major IOI. As its stating that shes into you enough that shes relying completely on you to provide entertainment - that is unless shes totally crazy about the event and is more concerned with it than you - my two cents