>>94520084well you have your characters, your scenario (lab partners) and your motivation (falling in love). Id say you are halfway there.
Now what you need is to connect it in an organic way that makes it so each scene leads to another.
so in this case, for example, you two go to get some last minute supplies and the road to the lab (its a rural school) its very dark and kind of scary. To get to this scenario, then you should write about the school being kind of badly equipped or the lab being far or how both you and the girl are chickens or one is a chicken and the other is pranking them.
Just try and get certain scenes done and then try and see how you would connect them