How do guys show they like u in school?

there's a guy in my class that acts different around me. Anything I should look for or how do u show that u like someone?
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Lately, he I’ve caught him looking at me and he would look away quickly. He is always in close proximity to me. Whenever I talk to him he stands really close to me even in group settings. He did something small but nice for just for me recently. He never talks about anyone else when he’s with me. His pupils are dilated around me. He mirrors my gestures and his eye brows are always slightly raised when he’s around me and he smiled more around me than others.
How do guys show they like u in school?
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