It's strange that I can tell by the way they write. I'm not always correct but many times I'd find someone writing as if they were an expert but you could just

It's strange that I can tell by the way they write. I'm not always correct but many times I'd find someone writing as if they were an expert but you could just tell they were only regurgitating something they read. They couldn't make a proper connection between things they were saying. I'd trick them in a way to reveal their age and way too often it was 15 to 17 years old. Sometimes 18 or 19. You can also read them saying they wanted to take CS when they graduated from school so you can glean from that they are probably in high school. Or I just flat out ask them (or accuse them).