My instructors told me not to holler at beginners when they can't apply corrections, that I should be patient. 

I think the reason why I holler at them (or get slightly agiated) is because:

a) As someone who even takes note of little details of a dance, trying to improve my skills, turning the dance into my own, I think that not attempting to do the choreo full out is a disrespect to dance. Even when they come to just "have fun", you chose to enroll in a dance studio founded by professionals (and housing more aspiring professionals), expect someone to be concerned about your skills. And I'm that person. 

b) I've been reminding them of the same correction for many times, sometimes even weeks, it's time you apply that freaking correction. 

c) Actually I don't even think I'm a strict teacher, you have not went through harsher training under my instructors. I have, and they holler at me sometimes. Even when I was a beginner. Maybe they knew that I was young, had potential, and wanted to be a professional. Either way, their hollering has benefited me and they should benefit you, not make you dread dance class. 

d) Just apply that damned correction, if you do not apply it you may get injured. Point that foot! And bend your knees or you will risk injuring them. It's not just about having fun, we practise basic moves so we can dance better, reduce risk of injury.

e) I'm a senior, but I was a beginner and when I was a beginner I hoped for a senior to give me advice that I could relate to. I even gave you a picture that taught you how to spot. I can choose not to give you corrections, not to help you, but I want you to do better, to be as good as me one day, without spending much time trying to figure out how and what to do, so that there is no need for you to spend more time to achieve the results. Because I had spent too much time on figuring out how to improve my skills. And I don't want you to spend so much time.

f) I am harsher on myself when I can't apply the correction. I go into little breakdowns and think about why am I not good enough. It's like that mistake would reduce my chances of being a professional.

Instead of trying to rush and be a very good dancer on the first day of class, just apply my damned correction. You have many mistakes, and correcting one of them means you are one step closer to being a good dancer. It's not about making big progress, it's about making little improvements and realizing how far you have gone when someone tells you that your dance has "lots of soul". 

I'll be less harsh, but I'm not sorry.