問題：Do you agree or disagree the opinion “the most important lesson can’t be learned in class”?
I agree that the most important lesson can't be learned in class for a couple of reasons.
First, try and error is a way to find out what works and doesn't work.
Although studying in class is critical, it's not enough to procure knowledge because most information we learn looks good on paper but won't work most of the time. Indeed, try and error, previous experiences, and learning from the mistakes have a huge impact on us obtaining knowledge because these can trigger our emotions.
In addition, learnig from experience is more effective.
For instance, when we learn foreign languages we can't apply it to real situations just by reading vocabulary books because utilizing knowlege and just remember are complitely different. In fact, no matter how much you read books, it's futile unless you can employ it.
Looks good on paper, but won't work ・・・机上の空論