“Anyone who writes down to children is simply wasting his time. You have to write up, not down.” Hi, I saw the above sentence. I googled "write up" and "write down" to understand its meaning. It says "Write down" is an idiom which means "make a note of", or "get something written". "Write up" is an idiom which means "write an account, record or essay" about something. But I think there's more to this sentence. Can somebody help me better understand what it means?