Consider the following scenario: I'm taking my kid (5 years old) to a coffeeshop and we do some 'math problems'. By math problems I mean that I explain him about the numbers, addition, counting and so forth. When I ask him to draw a number sometimes he doesn't do it properly so I tell him: "no, that's not good, let's try again". I don't like to reward/credit him if it's not ok but I also understand that he's 5 years old. I may also tell him not to lose focus and to try to complete the task. The way I choose to handle the 'lesson' is short, concise and fun (take my word here). To be clear, none of those lessons ever ends with tears and I fully understand that a child has a threshold (and I know how to spot it).
From time to time, there would be someone who will voice their opinion on my method. Example: "you should not say this or that but rather this and that." Or, "you should try this method it really works best for other kids." Sometimes they would even go an extra mile and leave me a note!
Usually, I tend to say "thank you for this pointer" and end the conversation promptly but the truth is that I find it insulting. Consider what would happen if I would interrupt an argument between 2 lovers and say something like: excuse me for interrupting but Sir, respectfully, you should apologize and buy her flowers. How would they react? would that be ok? of course not!
What am I asking?
What approach would one take to handle such situations? The way I choose to educate my child is my decision only and not a stranger's concern. I wish to focus on my child and not the audience but I also wish to draw a firm line when someone takes the initiative to confront me on a private issue and make suggestions what I should/shouldn't do.