Guy talk?

Approach him as a friend at first with no intention, its so much easier that way for talking to him later!

Don't let fear hold you back, find something You can relate to with him. Like maybe you noticed his hair style, or a cool/funny shirt, he was wearing, or maybe he answered a question really Well. Just compliment him.

Say "hey whats up" it works all the time lol you can even change the wording to be original
then let him lead the rest of the conversation

Ask for the homework. Don't call him, but after class, or maybe even after school, you could come up and ask him for the homework. Just say, "Hey, _____, do you know what the math homework is? I think I copied it wrong." Then try saying something else after he gives you the homework. Say, "So what's your favorite subject?" And so on, and so on. Then when you finally get the conversation going, you will be more comfortable near him and he will be more comfortable near you. If he flirts with you and is nice, try moving forward. You just need to take it all slowly. If he suddenly jumps out at you and acts very weird and not how you would like him to act, just slowly pull back and eventually stop talking to him. I hope this works and good luck.

Hey go for it just go up to him and ask what's up. Ask him for the notes in a class.

Ask him for class notes and then make a conversation!!

Use whatever you know about him to ask him a question about himself. If he doesn't respond much, just ask another question. Keep on going until he starts to open up.

It's best to try this when he doesn't have many friends around.