How to text a guy that doesn't know I have his number?

So I know this guy and he's one year older then me and last year we talked everyday because we had a class together and we talked the whole entire time. I was pretty sure he like me but then at the end of the year he graduated and now he's in high school and I'm stuck in middle school still. I have his number because we were going on this school trip and one of our close friends had to call him to make sure he was coming because he was really late and my phone made me save his number as a contact (I had a weird phone not an iPhone) I still wanna talk to him but I don't know how to. I was thinking doing the "accidental" text where I say I ment to send it to my friend and then explain how I got his number. Any advice?

I'd say go for it! You were cool with him and you guys talked a lot so he knows who you are. Send a text as an "accident" or maybe do something like "hey remember me" or something else fun and flirty. Don't be upset if he isn't elated to talk to you or maybe forgets you. I'm sure he will remember you though! Have fun and hope it all works out.