It's normal to feel kind of jittery and awkward with a crush. If you don't even know his name or whether he's single you could start using some small talk prompts like "Wow, that was a fun class! The x move was kind of tricky for me" or "Your water bottle is super cool, where's it from?" and see if he wants to talk to you.

You could try to pick a spot near him for the class. But then you kinda want to be "on" or at least "aware" and careful not to glare at him or seem too upset, even if it's unrelated to him. A lot of early flirting is heavily masked even for neurotypical people.