Does he like me back?

Ok so i am in middle school and i really like this boy named Derek!!! I dont know if he likes me back or not? Everyday after school i go pick up my brother and sister from an elementry school! he also picks up his brother at the same elementry school! He always looks at me! i am really good friends with his brother Isaac and one day I instant messaged Isaac on myspace and asked if Derek likes me! and he jst said "no" and nothing else! but i said "ok then!" but anyway Isaac knows i like Derek! i told him! but Derek always stares at me he tries to trip me every once in a while! and his friends always look at me! Sometimes he points at me to! his brother always tells me to jst go talk to him but i always say i am way to scared! he says ok wat ever ur loss! and i say i know i am jst really scared and everyday his brother tells me tht! but one day wen he didnt mention it i came up to Derek wen Isaac was standing behind him! Isaac pushed him closer to me! i said "hi" my friend likes him to and she also said hi and he didnt even look at her! he jst stared at me! he didnt say anything!! nothing at all!! Isaac was laughing in the background and after like 30 seconds of jst standing there looking at eachother Issac twisted him around really fast and said "why didnt u talk to her!?" and i could feel my face getting really red so i walked away i didnt hear his answer! i wish i would of stayed to hear his answer though! Please help me im wondering if i should ask him if he wnts to hang out sometime or not!? thanks! and i sent him a note telling him tht i like him and i was picking my bro up today and i was walking back home and he was sitting on a ledge and wen i ped him he stared at me took a deep breath and started to say "I" but then he looked down and wen i was all the way past him he got up and walked the other way!? i really want to know what he had to say itz bothering the heck out of me!