I'm a senior in high school. There's this girl in a lot of my classes that I have huge crush on. We talk somewhat regularly when walking from one class to the next, but 9/10 times it's about school. We don't really have time for any serious conversation anyway. Yesterday however, I sent her a message through Snapchat continuing a joke I made that day. She gave what seemed like a response where she legit found it funny, and I tried continuing the conversation. However, I only got responses of a couple words. We've talked on Snapchat a couple times before, but again mostly about school.

I want to try to have a somewhat decent conversation with her on Snapchat, but I don't know how to start a conversation completely randomly. I want to ask her out in the near future, but feel like we have to at least get past just talking about school first.

Edit: is it too early to message her again today when we talked yesterday?

Any advice/recommendations are appreciated :)