We get annoyed when kids say it, but it’s the most important word in the English language. Why? Because it enlightens.
If your kid asks you why they have to eat broccoli, it tests your logic too. If you just say because I said so, you’re not only selling yourself short, but you’re selling your kid short too. Without the proper logic, they can’t turn chores into habits. So by being lazy with your logic, you’re keeping them from developing reproducible behaviors, and avoiding the question.
If you can’t answer the question, maybe your logic on the subject is undeveloped, or is unsound. So this question not only helps your children learn the reason to do something, but it helps question your logic, which may be the most important part of all.